Reference:Movements

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Find a caliber by family below, then compare its markings and specifications with the individual watch reference. Several early caliber attributions remain disputed; those entries name the competing descriptions.

Quick jump

Prince (shaped)

300 7½ T.S. 300 310 360 HW 350 T.S. 1759

Oyster Perpetual automatic

1130 OP 1160 1161 2030

Bubbleback / early automatic

520 420 50 620 630 635 700/710 600 59 A260 A296 A.295 645 720 automatic (lot attribution) 740 745

Calendar / moonphase

A.295 CPL

Early Oyster (lot attribution)

2849 (Cal. 500 attribution)

Oyster / Oysterdate Precision

1210 1215 1216 1220 1225 1200

Cellini and dress watches

1600 7040

Vintage sport (1950s–80s)

1030 1035 1036 1040 1050 1065 1066 1530 1520 1535 1525 1560 1565 1570 1575

Modern sport (1988–2023 coverage)

3000 3035 3075 3085 3130 3132 3135 3175 3185 3186 3187 3230 3235 3285

Milgauss

1080 1580 3131

Early chronograph

13

Daytona chronograph

72 72A 72B 722 722-1 727 4030 4130 4131 4132

Day-Date

1055 1555 1556 1566 3055 3155 3156 3255

Oysterquartz

5035 5055

Rolex movements

This page covers calibers used by Rolex families in the wiki, including several numbers with no confirmed fitment. Reference pages document individual applications.

A caliber designation identifies a movement type. An individual movement number and the case serial belong to separate numbering systems. Comparing their numerical size does not establish which component was made first. The serial-number guide explains the limits of case dating.

Aegler in Bienne made most of the mechanical movements covered here. The firm supplied Rolex as an independent manufacturer before becoming its subsidiary in 2004.

The caliber entries describe balance materials, hairsprings and shock protection where documented. A technology's introduction at Rolex does not mean that every movement received it in the same year.

== Early chronograph movement

The early Oyster chronograph references use Valjoux ébauches, with Rolex caliber designations that should be kept distinct from the maker’s base number. Available auction records support a limited Cal. 13 / Valjoux 23-family entry. Ebauches S.A.'s 1951 technical guide labels a two-pusher, 13-ligne movement “VZ 23” (technical guide, 2nd edition March 1953). That nomenclature does not establish Rolex fitment. The Cal. 13 evidence discussed here concerns the 3525 and does not identify every early Rolex chronograph movement.

Ref. 2021 is a pre-Oyster monopusher. Published descriptions give movement sizes from 13 to 16½ lignes; Uhrenkosmos names a Valjoux VZ in one early monopusher, while auction catalogues describe different executions. The available records do not support a reference-wide caliber assignment. Keep these descriptions separate from the Cal. 13 entry below. Uhrenkosmos, early monopusher movement Phillips, case 12'010 Cambi, steel case 14xxx

Auction records describe ref. 2303 with 17-jewel lever movements; several Antiquorum lots measure them at 10½ lignes. Christie’s records a case-band pusher on one example, while other catalogues describe crown-operated monopushers. The lot descriptions leave caliber and maker unnamed, so a Valjoux 23 / Cal. 13 assignment would go beyond them. Antiquorum, case 17890 Christie’s, case 022310

Cal. 13

detail	value
type	Manual chronograph
base family	Valjoux 23; auction catalogues variously specify 23 VZ or only Cal. 13
size / jewels	13 lignes and 17 jewels in the Antiquorum Nutting record; Sotheby’s records 17 jewels for case 372822
fitment documented here	3525; other early reference assignments require their own source check

Antiquorum identifies Cal. 13 and a 13-ligne, 17-jewel movement in the 3525 delivered to Clive Nutting; its Leon Brownlee catalogue also names Cal. 13. Sotheby’s 2020 catalogue for a 3525 gives manual winding and 17 jewels but no caliber number. The recurring Valjoux 23 attribution is supported by specialist references and auction descriptions, but the precise movement marking should be read from the individual watch. Cal. 13 is Rolex’s designation in these records; it is not a claim that Rolex manufactured the Valjoux chronograph base. See the pre-Daytona chronograph guide.

Prince (shaped movements)

The Prince family uses Aegler shaped movements. Wilsdorf and Aegler patented the layout in 1927 as a "shaped watch movement with a seconds dial." It placed the winding barrel at one end of the rectangular movement and the balance at the other, leaving room for a larger balance wheel and mainspring barrel than rival shaped calibers of the period. The larger balance improved precision, while the larger barrel extended the power reserve.

Aegler remained an independent supplier until Rolex bought the company from the Borer family in April 2004. "Aegler" and "Rebberg" refer to the same firm; Rebberg was the street in Bienne where it stood. Aegler also made movements for Gruen. The architectural sibling of Cal. 300 sold in the United States as the Gruen Techni-Quadron, designated Cal. 877. Gruen-stamped movements sometimes appear in Rolex Prince cases, but Cal. 877 was never a Rolex caliber number.

Prince grades run Prima → Extra Prima → Ultra Prima, with higher jewel counts, more adjustment positions, and stricter chronometer testing. Only Extra Prima and Ultra Prima watches carry "Chronometer" or "Observatory" dial marks. Rolex submitted Prince movements to the National Physical Laboratory at Kew for rate certificates independent of the Swiss Bureaux Officiels Suisse de Contrôle. Its often-cited 1914 Class A Kew certificate belongs to an earlier ladies' wristwatch movement, while Prince testing at Kew-Teddington began in 1928.

The Prince Imperial pocket watch, ref. 1645, has a shaped manual movement. Sotheby’s records a 17-jewel Class A Observatory movement, number 1,000,823; Antiquorum describes other examples as 17-jewel Ultra Prima or Observatory movements in several line sizes. The Vintage Rolex Field Manual lists 5096 in its caliber column for the 1645. Auction descriptions and the inspected movement photographs do not confirm that number on a movement, so it remains a book attribution rather than an established caliber.

Cal. 300

Cal. 300, Extra Prima grade, rectangular Prince architecture, Bonhams lot photo

detail	value
type	Manual
jewels	15 (Prima) · 18 (Extra/Ultra Prima)
frequency	18,000 vph (2.5 Hz)
power reserve	~50h
size	7½ × 14½ lignes / 16.9 × 32.7mm
escapement	Lateral lever
shock	None

Cal. 300 is the original Prince movement, made from 1928 to 1935. Christie's describes all three as the same movement base, with interchangeable parts and the balance bridge identifying the original execution. Prima movements have 15 jewels and six-position adjustment; Extra Prima and Ultra Prima versions have 18 jewels, six-position adjustment, and sometimes a Chronometer marking. David Boettcher identifies the additional jewels as two end-stones on the escape-wheel pivots and a top bearing on the centre wheel. Early movements carry the grade wording on the ratchet wheel, while later examples place it on the main train bridge. The photographed Extra Prima, marked "Observatory 6 Positions," shows the later convention.

Balance metallurgy changed gradually. Examples from 1928 use a bimetallic balance with a plain Breguet spring; by the mid-to-late 1930s, documented movements have both monometallic and bimetallic balances paired with Elinvar-alloy hairsprings. No exact transition year is established. "Patented Superbalance" on later ratchet wheels and bridges refers to Aegler's Swiss patent CH196706, filed in August 1936 and granted in March 1938. A movement carrying the mark postdates the grant. The recessed timing screws are often said to reduce air resistance, but Boettcher reads the patent as a way to maximize the balance's radius of gyration within the available space.

The Cal. 300 examples described here have no identified shock-protection system. Incabloc dates the start of its production to 1933 and the later lyre-spring design to 1938. Those dates alone cannot establish the fittings in a particular Prince.

Several UK auction catalogues treat the three- and four-digit numbers found on movements in refs 1862, 1490, and 1855 as calibers. The documented numbers are 510, 579, 841, 1004, 1130, and 1439, with weaker evidence for 701 and a single record of 1759. They are almost certainly movement serials read from the plate. Continental catalogues identify the same movement class by grade and the T.S. size code instead. Cal. 414 and Cal. 527 have no documented connection to the Rolex Prince. The number 971A is a Prince case reference, not an established caliber designation; Antiquorum catalogued that reference in 1989 with a T.S./300-family movement. Fabsuisse labels the movement in its separate ref. 3937 dealer listing “Cal. 971A,” but the auction records reviewed here do not confirm that designation. Treat it as an unverified dealer attribution unless a readable movement marking supports it.

Cal. 7½′′′ T.S. 300

Cal. 7½′′′ T.S. 300, marked "Rolex World's Records," "Rolex Chronometer," "18 Rubies, Ultra Prima"

detail	value
type	Manual
frequency	18,000 vph (2.5 Hz)
power reserve	~50h
size	7½′′′ rectangular
escapement	Lateral lever
balance	Monometallic
regulator	Micrometer

"T.S." is Rolex's size-family code for this 16.9 × 32.7mm architecture, catalogued by Christie's as "cal. T.S. Ref. 300." There is no support for the common expansion "Très Soigné." The six-position Ultra Prima execution ran from 1932 to 1938 with a lateral lever escapement, monometallic balance, micrometer regulator, Breguet overcoil hairspring, and rhodium plating. On the 1527 Railway, Extra Prima movements outnumber Ultra Prima examples, reversing the pattern seen on the 1490. An eight-position Ultra Prima marked "Officially Tested in Eight Ways" is documented on a 1931 bamboo-bracelet example sold by Mondani in 2006.

Antiquorum's 2017 listing for Prince ref. 1768 case 019784 describes a 7½-line T.S. 300 with 15 jewels; its listing has no movement photograph. Uhren-Muser's 2023 photograph of case 019794 shows an Extra Prima movement marked 17 Rubies. The watch and box images resemble Antiquorum's example, but the case numbers differ by one digit, so the lots may be repeat listings. The T.S. 300 illustrated here is marked 18 Rubies. Keep each count with its photographed or catalogued example. Antiquorum, 2017, lot 118 Uhren-Muser, 2023, lot 266

Cal. 310

detail	value
type	Manual
jewels	18
size	7½′′′ rectangular (19 × 49mm cased)
escapement	Lateral lever
balance	Superbalance, 6-position
regulator	Micrometer

Cal. 310 is the centre-seconds member of the T.S. family, used in the wedge-shaped 3361 Aerodynamic, 3362, and 3937 Prince group. Antiquorum described a 3361 in 2000 as a rhodium-plated 7½-ligne movement with 18 jewels, lateral lever escapement, six-position Superbalance, self-compensating Breguet balance spring, and micrometer regulator, in a 19 × 49mm case. That catalogue does not print the number 310, so the caliber attribution is less secure than the architecture and specifications. Movement production ended in 1938, but Aegler stock remained in Rolex cases through 1952. The difference between a movement number and case number does not independently prove a stockpiling interval.

Cal. 360 HW

Cal. 360 HW, marked "Rolex, 15 Rubies, Swiss Made"

detail	value
type	Manual
jewels	15–18

The architecture of Cal. 360 is disputed. Christie's describes a 1938 ref. 2835 "Prince Elegant" with a tonneau-shaped 15-jewel movement, and Charles Jarman's The Rolex Reference Guide (4th edition) calls Cal. 360 a manual, small-seconds, tonneau-shaped movement with a SuperBalance. Watch Doctor’s online chart instead lists a rectangular, 18-jewel movement measuring 18 × 27mm. The page does not identify an underlying Rolex document.

Christie's also describes a rectangular 17-jewel Cal. 360 in 1937 Precision ref. 3140 case 41,362. Monaco Legend gives Cal. 360 for another 1937 ref. 3140, case 41,465, but no jewel count. These are catalogue attributions to individual watches; they do not settle the conflicting movement descriptions. Christie’s, 2008 lot 13; Monaco Legend, 2024 lot 219

Jarman dates Cal. 360 to 1937. The expansion of the HW designation remains unconfirmed; it should be retained as a designation rather than expanded to Hans Wilsdorf. The differing shape and jewel descriptions need comparison with the movement in the individual watch. Ineichen’s 2016 catalogue attributes C.360 to a Prince ref. 1880 and describes a nickel-plated lever movement. That is one lot-level attribution; it does not resolve the conflicting descriptions above. Ineichen, Auction 164, lot 133

Numbered Prince movements (510, 579, 701, 841, 1004, 1130, 1439)

Seven numbers circulate in Prince catalogues as "calibers": 510, 579, 701, 841, 1004, 1130, and 1439. In the Prince examples reviewed here, the bare numbers are most likely movement serials rather than caliber designations. This interpretation is specific to the Prince plates; auction catalogues separately identify a Rolex automatic Cal. 1130 in Oyster Perpetual ref. 6548 examples, discussed below.

Photographed Prince plates carry a grade legend, jewel count, "Swiss Made," and a bare number stamped beside the "NN RUBIES" wording, but no caliber designation. Grade legends include Prima, Extra Prima, Ultra Prima, Observatory Quality, Officially Tested in Eight Ways, Timed 6 Positions, and For All Climates. The bare number ranges from four to seven digits. Ultra Prima 18-jewel examples with otherwise matching plates carry 1260, 1439, and 1759 in that position, confirming that the stamp varies within one movement type.

Continental auction catalogues identify these movements by size code and grade, such as "cal. T.S. 300" or "7½′′′ T.S. 300, Observatory Quality." UK lots that print a "Cal." figure also give a separate case or serial number, indicating that the supposed caliber was read from the movement. The specifications also overlap: 1439 and 1759 both describe an 18-jewel Ultra Prima movement adjusted to six positions. A bare mainplate serial has likewise appeared in print as a "1240 calibre movement."

Auction descriptions use these numbers, but the available plate evidence points to movement serials.

number	documented on	catalogue text	notes
510	Prince Brancard ref. 1855, serial 143**, circa 1930	"17-jewel Cal.510 manual wind movement tested to 8 positions"	8-position adjustment, against the more typical 6
579	stainless steel ref. 1862, circa 1935, case No. 103	"17-jewel Cal.579 manual wind movement" (Bonhams London)	single lot; the trailing "T" in some listings is absent from Bonhams' catalogue text
701	one photograph showing "ROLEX PRINCE 701" on a 1930s piece	none	no recorded jewel count, adjustment count, or technical description; no auction or catalogue attribution
841	ref. 1862 circa 1930, case No. 10403	"17-jewel Cal.841 manual wind" (Bonhams London; resold through Tajan in 2019, the same watch catalogued twice)	a separate listing gives 15 jewels for a "Cal. 841T" on a different 1862; a caliber designation would not change jewel count
1004	ref. 1862, Glasgow import mark for 1936, serial 176**	"17-jewel Cal.1004 manual wind movement tested to 8 positions" (Bonhams, December 2015)	white gold bezel, fixed wire lugs, gilt brick-link bracelet
1130	9K yellow gold ref. 1490, case 30280	"cal. 1130 manual winding lever movement, 16 jewels"	lowest jewel count recorded in the group
1439	Prince Chronometre ref. 1490, Glasgow import mark for 1937, serial 307**	"18-jewel Cal.1439 manual wind movement timed to 6 positions" (Bonhams)	same 18-jewel, 6-position Ultra Prima specification as Cal. 1759 below

Cal. 1759 is the same phenomenon. It remains separate because the photographed watch preserves matching movement and caseback markings, but the number appears in the serial position on an Ultra Prima plate and is documented in only one regional UK auction.

Cal. 1759

Cal. 1759, "1759, 18 RUBIES, ULTRA PRIMA," with its matching case back

detail	value
type	Manual
jewels	18

This circa 1937 Ultra Prima Chronometer has 18 jewels and six-position adjustment. Gardiner Houlgate catalogued it in a 9ct ref. 1862 with 1937 Glasgow import hallmarks as a "cal. 1759 Ultra Prima Chronometer 18 jewel movement timed 6 positions." The photographed example retains its matching caseback, engraved "1759, 18 Rubies, Ultra Prima" alongside "31 Records Universels" and a retailer stamp. The identification rests on this single regional UK auction lot.

Cal. 350 T.S.

Cal. 350 T.S., Extra Prima grade, 15 rubies, timed to 6 positions, in a ref. 1491 jumping hour

detail	value
type	Manual
jewels	15 or 18 (documented both ways)
size	16.9 × 32.7mm (T.S.)
escapement	Lateral lever
balance	Monometallic

Cal. 350 is the jump-hour member of the T.S. family, alongside the small-seconds Cal. 300 and centre-seconds Cal. 310. Christie's and Sotheby's catalogue it in the 1491 Brancard Jumping Hour as an 18-jewel, chronometer-rated movement on the T.S. base. Another 1491 has a 15-jewel Extra Prima movement; Ultra Prima examples have 18 jewels. Jewel count varies with grade. The jump-hour disc works on much the same principle as the later Datejust date disc. Surviving examples carry Glasgow import hallmarks from 1930–31, consistent with the T.S. base's 1928–35 production window.

The 1491 has a deeper case than the 1490 to accommodate its jump-hour mechanism. Case depth is one comparison point; the movement, module and case markings must agree as well.

Cellini and dress-watch calibers

Auction catalogues identify manually wound Cal. 1600 in late-1960s Cellini-labelled ref. 3735 examples. Rolex's 1978 service booklet supplies the movement dimensions and rate; the auction descriptions supply reference fitment and jewel count.

Cal. 1600

detail	value
type	Manual-wind, round
size	9¼ lignes
frequency	19,800 beats per hour
jewels	19 (Farsetti catalogue)
fitment documented here	Cellini-labelled ref. 3735 examples in Farsetti and Fortuna auction records

Rolex's 1978 Technical and Service Information lists Cal. 1600 as a round 9¼-ligne movement running at 19,800 beats per hour. Farsetti and Fortuna attribute Cal. 1600 to their respective 3735 watches; Farsetti lists 19 jewels. Since neither auction entry includes a movement photograph, these remain catalogue attributions for the individual examples.

Sources: Rolex Technical and Service Information, third edition (1978); Farsetti, lot 107363; Fortuna, lot 113.

Cal. 7040

Rolex's archived Cellini Prince descriptions identify Cal. 7040 as a shaped, manually wound, chronometer-certified movement with Paraflex shock absorbers, a Breguet overcoil and about 72 hours of reserve. Rolex's 2015 price list gives 21 jewels; its archived product page gives 28,800 beats per hour.

suffix	reference	Rolex's listed version
7040-1	5440/8	18 ct yellow gold; Clou de Paris dial
7040-3	5441/9	18 ct white gold; silver Godron Circulaire or diamond-pavé Godron dial
7040-2	5442/5	Everose gold; Rayon Flammé de la Gloire dial
7040-4	5443/9	18 ct white gold; double Rayon Flammé de la Gloire dial

Rolex's model-specific text assigns Cal. 7040-3 to both 5441/9 dial versions. Antiquorum's 2008 catalogue calls case D758994 Cal. 7040-1; Christie's and Sotheby's identify other 5441/9 examples as 7040-3. Keep Antiquorum's label with that lot; the available record does not resolve it. Rolex archived Cellini Prince product page, 2014; Rolex Netherlands price list, 2015; Antiquorum, Geneva, 2008; Christie's, case D774253; Sotheby's, Geneva, 2010, lot 132.

Rolex's archived 5442/5 page assigns Cal. 7040-2, as do Christie's, Kaplans and Sotheby's examples. Antiquorum's 2008 and 2022 catalogues call two 5442/5 movements 7040-1. Retain those labels with their lots; the available images do not establish a separate reference-wide movement version. Rolex archived 5442/5 product page, 2014; Christie's Geneva 2009, lot 315; Kaplans, Stockholm, 2013, lot 469; Sotheby's, 2021; Antiquorum, Geneva, 2008, lot 231; Antiquorum, Monaco, 2022, lot 198.

Early manual-wind Oyster examples

The early cushion-case Oyster references used manual movements, but the available catalogue descriptions do not support one movement assignment for every reference. For ref. 1069, Antiquorum describes a 15-jewel 11-ligne manual movement on its 2003 example; Christie's describes an unnamed 15-jewel lever movement, and a dealer-photographed example shows a 17-jewel Rolex movement. Keep each description with its watch. Aste Bolaffi's Marconi Oyster has a 15-jewel FHF 30-based movement and the number 1069 on its case, but the catalogue does not identify that number as the reference. Antiquorum 2003; Christie's; dealer photo set; Aste Bolaffi 2022

For ref. 1072, Antiquorum describes 10-ligne, 18-jewel movements in two examples. Bonhams calls a separate example a 15-jewel Prima. Cool Auction labels the movement Cal. 10½ and reports 15 jewels, 18,000 beats per hour and a maximum 38-hour reserve on a Bucherer-signed watch. The same dealer attributes a Superbalance and Breguet hairspring to that movement. Hess Fine Auctions reports a manual 15-jewel movement in its 2023 lot. Watch Collecting describes another example as manual-wind but gives no caliber or jewel count. Toovey’s title calls its circa-1938 example Ultra Prima but gives no movement specification. The Cool Auction caliber label has no corroboration in the other records; the lots do not establish a single movement assignment or grade across the reference. Antiquorum, Hong Kong, 1997; Antiquorum and Bonhams archive; Cool Auction; Hess Fine Auctions, lot 3211; Watch Collecting; Toovey’s

For ref. 1073, Antiquorum names a 10½-ligne Extra Prima movement with 15 jewels. David Boettcher reports that Prima movements he has examined are generally 15-jewel, while the Extra Prima and Ultra Prima examples he has examined have 18 jewels. Antiquorum’s description is an exception to that pattern; its catalogue does not explain the mismatch. Christie's describes a 15-jewel Prima, and Bonhams calls another 15-jewel movement Ultra Prima. The lot descriptions give no shared caliber number or reference-wide grade. Antiquorum; Christie's; Bonhams archive; David Boettcher, movement-grade survey

A scanned Oyster case-and-crown table lists ref. 2416 at 10½ lignes in its “calibre size” column. TimeAnagram gives the same figure in a dealer movement field. A Hodinkee photograph of case 32342 shows a manual movement stamped “Rolex 15 rubies”; Bonhams describes case 37425 as a patented Superbalance. Christie’s identifies case 36776 with an Ultra Prima movement jewelled to the third. These catalogue descriptions give no numbered caliber for the reference. Oyster case-and-crown table, ref. 2416 row; TimeAnagram, ref. 2416 item 57171; Hodinkee, case 32342; Bonhams, case 37425; Christie’s, case 36776, sale 5004 lot 98

For ref. 2849, two Antiquorum catalogues identify 17-jewel Cal. 500 movements in separate watches dated 1937. Antiquorum’s 2006 note also says Cal. 500 was produced from 1943 to 1953, which conflicts with that lot’s own date and attribution. These attributions belong to those catalogue examples; the records do not settle the reference’s movement range. Antiquorum, case 87,464; Antiquorum, case 36,618.

Oyster Perpetual automatic movements

Rolex automatic Cal. 1130

Auction catalogues identify an automatic Rolex Cal. 1130 in Oyster Perpetual ref. 6548 examples; Dorotheum and Antiquorum describe 26 jewels. This is separate from the bare 1130 number on the Prince plates above, where it appears in a movement-serial position.

Ranfft dates Cal. 1130 to 1955. Dorotheum lists it in a 6548 dated circa 1942/43, while Jones & Horan lists it in a circa-1957 6548 with serial 230918, only 334 higher than Dorotheum’s 230584. These records conflict; they do not establish a 6548 production interval or resolve which date or identification is wrong. The available sources also do not establish beat rate or a full technical specification. Verify the movement marking on the individual watch. Dorotheum; Jones & Horan, lot 485; Ranfft; Antiquorum

Cal. 1160

The Vintage Rolex Field Manual lists Cal. 1160 on base 1100, with automatic winding, 26 jewels and a rate of 19,800 vph; its table gives 1968. Sotheby's and Cambi catalogue Cal. 1160 in ref. 6548 watches dated circa 1945 and circa 1957. Those lot dates conflict with the Field Manual entry. Its table is not a ref. 6548 fitment record, and the available sources do not resolve whether the discrepancy comes from a lot date or caliber identification. The Vintage Rolex Field Manual; Sotheby's, lot 8773; Cambi, lot 186

Cal. 1161

The Field Manual lists Cal. 1161 on base 1100, with automatic winding, 26 jewels and 19,800 vph; its table gives 1970. Sotheby's attributes Cal. 1161 to a ref. 6548 dated circa 1964. Bonhams assigns it to a circa-1968 watch catalogued jointly as refs. 6548/6549. These catalogue dates precede the manual's entry; the sources do not establish the 6548 fitment interval or resolve the conflict. The Vintage Rolex Field Manual; Sotheby's; Bonhams, lot 161

Cal. 2030

detail	value
type	Automatic, sweep seconds
jewels	28
hacking	Yes
fitment documented here	6718; exact-reference catalogues list Cal. 2030 in individual watches

Rolex's 1978 Technical and Service Information describes Cal. 2030 as automatic, with sweep seconds, 28 jewels and hacking. It distinguishes the calendar-equipped Cal. 2035. Sotheby's and Antiquorum catalogue Cal. 2030 in individual 6718 watches. The exact-reference catalogues document those individual fitments; broader 6718 fitment and production dates remain unresolved. Rolex, Technical and Service Information, 3rd ed. (1978); Sotheby's, lot 8136; Antiquorum, lot 252

Bubbleback and early automatic

Bubbleback and early Oyster Perpetual references use a distinct family of self-winding calibers. They followed the Prince's manual shaped movements and preceded the standardized post-war automatic line. The "bubble" refers to the domed caseback needed to clear the full-rotor automatic mechanism. It was not a bumper system, although many competing automatics still used one.

Cal. 420

detail	value
type / size	Automatic centre-seconds; catalogue prints “7¾” and separately lists Ø 19.4 mm
reference attribution	Possible ref. 5002 attribution from James Dowling; 5002 catalogue descriptions of subsidiary seconds conflict with Cal. 420’s centre-seconds description

Rolex's parts catalogue establishes Cal. 420's type and specifications, but it does not list ref. 5002 as a fitment. James Dowling's reference-specific listing assigns the caliber to a 5002. The seconds-layout mismatch leaves that assignment uncertain; available auction images show no readable movement stamp. Antiquorum describes an 8-ligne movement size in one 5002 catalogue entry. Rolex spare-parts catalogue ref. 170, Cal. 420; James Dowling, ref. 5002 listing

Cal. 520

detail	value
type	Automatic; listed for ref. 1858 in the Vintage Rolex Field Manual
jewels	17 in Aste Bolaffi lot 34 and Antiquorum’s 6006 lot 253; 19 in Antiquorum lots 229 and 233
movement size	8¾ line in several catalogues; 9¾ line in Antiquorum Hong Kong lot 47
other recorded details	Lot-specific descriptions include a straight-line lever escapement, screwed balance, and Breguet hairspring

The Field Manual lists Cal. 520 for ref. 1858; Antiquorum attributes it to the 1952 ref. 6006, case 927300, and reports 17 jewels. Aste Bolaffi identifies movement 1143 as Hunter 8¾ (520), and Vintage & Prestige and WatchNet list Cal. 520 for their ref. 1858 examples. Hodinkee's 2024 family guide instead assigns Cal. 620 to the first series beginning with ref. 1858. Phillips and Antiquorum's 2006 and 2013 lots list 8¾-line movements; Antiquorum's 2021 Hong Kong entry gives 9¾ line without naming a caliber. The lots report 17 jewels for Bolaffi movement 1143 and 19 for the two Antiquorum movements.

Aste Bolaffi identifies movement 1143 as Cal. 520 in its lot description; the caliber stamp is not legible in its photograph. WatchNet's image of product A-6378 shows English service labels, including “CONNECTING CASE SCREWS.”

Cal. 50 (3130 auction attribution)

Sotheby's catalogued one stainless-steel ref. 3130 as a manual-wind Cal. 50 with 17 jewels and subsidiary seconds ([2013 lot 197](https://www.sothebys.com/en/auctions/ecatalogue/2013/watches-n09002/lot.197.html)). The lot is the only application of Cal. 50 checked here. Its caliber attribution, jewel count and configuration should remain tied to that catalogue entry until a movement stamp is inspected; this page does not establish a production range or other reference fitment.

Cal. 620

Cal. 620, EmmyWatch

detail	value
type	Automatic
jewels	17
frequency	18,000 vph (2.5 Hz)
power reserve	35h
size	11½ lignes / 26.4mm × 7.5mm
escapement	Straight-line lever
balance	Superbalance (monometallic)

Derived from the manual Cal. 600, Cal. 620 became the base for Rolex's early full-rotor automatic family. Antiquorum catalogues individual examples with 17 to 20 jewels, against the table's 17-jewel specification. Earlier 1940s movements have a swan-neck micrometer regulator without shock protection; by the early 1950s, an index regulator and shock absorber appear.

Ineichen’s Auction 166 catalogue identifies Cal. 620 in one 1940s ref. 4643, case A60906 (p. 143). Keep that attribution with the auction lot; it does not establish a reference-wide caliber assignment.

Marcus Siems assigns Cal. 620 to ref. 3716 in his Empire study. That conflicts with Antiquorum's Cal. 635 listing for case 156649 and the Cal. 635 entry in Colin A. White's reference table. Catalogues describe several 3716 movements as 9¾ lignes, while the specification above gives Cal. 620 as 11½ lignes. The published records do not reconcile the caliber assignments. Siems, “The Deceptive Oyster”; Antiquorum, 2008, lot 284.

The rotor is a unidirectional "Perpetual" type that turns through 360 degrees without bumpers or buffers. It is engraved "ROLEX PERPETUAL / CHRONOMETER / SWISS MADE / PATENTED / SUPER-BALANCE," while the three-screw, 18mm cover plate reads "VIS TIRETTE / PATENTED / TRIGGER SCREW." Cal. 620 powered early Bubblebacks. Rolex dates the introduction of its Perpetual rotor to 1931, but that historical account does not name the caliber. Cal. 630 and the related 635 and 645 developed from the same architecture.

Published records for 3134 show both subsidiary- and centre-seconds layouts; identify the caliber from its movement marking. Antiquorum’s 1995 Milan lot gives 9½ lignes; Antiquorum’s 1992 lot and Exclusive Timepieces lot 227 give 9¾. Klöter describes lot 443’s anchor movement as intact, without a caliber or winding type. Seconds layout alone cannot distinguish Cal. 620 from 635 or Cal. 630 from 645. See the Klöter catalogue and reference article for lot-level evidence.

Cal. 630

Cal. 630, EmmyWatch

detail	value
type	Automatic
jewels	17
frequency	18,000 vph (2.5 Hz)
size	26.0mm
escapement	Straight-line lever
balance	Monometallic

Launched in 1937, Cal. 630 was chronometer-certified under the period Swiss testing system, adjusted to seven positions, and fitted with a Breguet hairspring. One secondary source gives 18 jewels rather than the table's 17. The movement developed directly from Cal. 620 and shares its "Vis Tirette *** Patented *** Trigger Screw" cover-plate marking. Its rotor and bridge also carry the same "Rolex Perpetual Chronometer, Swiss Made, Patented, Super-Balance" signature. The caliber number stamped in the small box on the bridge distinguishes the two.

Antiquorum catalogues ref. 4392, case 607544, with Cal. 630 and a small-seconds dial. The same lot says the dial is probably reprinted, and its photographs do not show the movement. Keep the caliber and dial layout as a conflicting catalogue description, not a verified Cal. 630 small-seconds variant. Antiquorum, lot 105

The Field Manual also lists Cal. 630 against the 3372 suffix variants. Antiquorum explicitly names Cal. 630 in a 3372 with centre seconds ([New York lot 436](https://catalog.antiquorum.swiss/en/lots/rolex-lot-23-436)). The same manual lists subsidiary seconds for one 3372/3 entry, while Christie's catalogue describes a 3372 with small seconds and a 9¾-ligne, 17-jewel movement but gives no caliber number ([case 474309](https://www.christies.com/lot/rolex-oyster-perpetual-chronometre-bubble-back-ref-5091692/?intObjectID=5091692&lid=1)). Keep those statements tied to their sources; they do not establish a Cal. 630 small-seconds variant.

Henrik Korpela identifies Cal. 630 NA in one gold watch catalogued as ref. 6074; its movement number is 56567. Korpela's photographs show 6030 and 6031 scratched out on the caseback before 6074 was stamped over them (SJX restoration). Antiquorum's 1992 platinum 6074 lot gives a 9¾-ligne, 17-jewel movement with antishock but names no caliber (lot 67). Keep each description attached to its watch; the records do not establish a reference-wide caliber assignment.

Cal. 635

Cal. 635 belongs to the early automatic family related to Cal. 620. General movement references describe a subsidiary-seconds layout, 17 jewels and a larger movement than the 9¾-ligne measurements in two 3130 auction entries. Antiquorum catalogued 3130 cases 54932 and 474617 with Cal. 635, 19 jewels, 9¾ lignes and subsidiary seconds ([lot 256](https://catalog.antiquorum.swiss/en/lots/rolex-lot-108-256); [lot 169](https://catalog.antiquorum.swiss/en/lots/rolex-lot-108-169)). Christie's identified case 443093 as Cal. 635 with 19 jewels but centre seconds ([2007 lot 2858](https://www.christies.com/en/lot/lot-5008631)). The latter catalogue description conflicts with the usual seconds layout. Without a visible caliber stamp, keep the centre-seconds attribution attached to that lot; do not treat it as a confirmed Cal. 635 variant.

Antiquorum's 2008 catalogue assigns Cal. 635 to ref. 3716, case 156649, and describes a 9¾-ligne, 19-jewel movement. That listing conflicts with the Cal. 620 attribution in Marcus Siems's Empire study; the movement-size description does not by itself establish a numeric caliber. Antiquorum, lot 284.

Ref. 1925 lots name Prima or Ultra Prima grades. Antiquorum describes a 9′′′, 15-jewel Prima; Christie’s names Prima on its 1928 example and Ultra Prima on a 1930s octagonal watch; Sterling Vault records a 15-jewel Ultra Prima. The auction record supplies grade names rather than a numeric caliber assignment. Antiquorum also describes a 1948 ref. 2081 with a 10-ligne, 15-jewel Prima; that lot does not name a caliber. Antiquorum, lot 675

Cal. 10½ Hunter

Cal. 700, the 10½-ligne Hunter, monometallic Superbalance, shown in its Oyster case

detail	value
type	Manual
jewels	15–18
frequency	18,000 vph (2.5 Hz)
size	10½ lignes
escapement	Straight-line lever
balance	Superbalance, 6-position
regulator	Swan-neck micrometer

This Aegler-supplied 10½-ligne hand-wound family uses the 700/710 architecture. It has a straight-line lever escapement, monometallic Superbalance adjusted to six positions, self-compensating Breguet balance spring, and swan-neck micrometer regulator, with no documented shock protection. Antiquorum names Cal. 700 in its catalogue for ref. 3358, case 51,419, with 18 jewels; its ref. 2081 case 599,744 lot names the same caliber and grade but records 15 jewels. The discrepancy is unresolved, so the jewel count is left unspecified here. Antiquorum, ref. 3358 Antiquorum, ref. 2081 The movement powers the original Air-King 4925 and its Air-Lion, Air-Tiger, and Air-Giant siblings, including the sub-seconds 4365, mid-size 4444, and 4647 Hunter Precision. Its architecture links the pre-war Prince and Bubbleback movements with the post-war automatic Cal. 1030. Cal. 700 and 710 are hand-wound movements; Cal. 720 belongs to the automatic branch. TimeAnagram lists Cal. 710 for a manual ref. 3121 and shows an open-movement photograph marked Rolex 15 Rubies and Superbalance, but no readable caliber number. Keep Cal. 710 as the seller’s attribution to that watch. White’s *The Vintage Rolex Field Manual* maps ref. 5031 to Cal. 710 in a reference table, but auction catalogues describe 5031 examples as automatic date watches. Christie’s listing records movement number 37519 but no caliber; Antiquorum’s 1995, 1999 and 2009 entries do not name a caliber and report differing sizes and jewel counts. Sotheby’s 2020 and 2022 entries say only “automatic.” The available records do not resolve the conflict, so the 5031 is not assigned to Cal. 710, A.295, 740, or 745 here.

Auction catalogues identify manual Cal. 710 in three ref. 6082 watches: Antiquorum cases 784516 and 721396, and Monaco Legend case 810693. Colin White’s reference table also pairs 6082 with Cal. 710. Antiquorum’s Hong Kong 2021 narrative calls case 721396 self-winding, while its movement field names Cal. 710. Kibble Watches and Watch.de assign Cal. 1210 to separate examples; Watch.de reports case 721965, a 1961 date and movement no. 1162170. Neither dealer listing provides a readable movement photograph, so these remain seller attributions. The 6082 article keeps the conflicting records tied to individual watches.

Catalogues describe hand-wound Kew A movements in refs. 5056 and 6210 as 10.5-ligne or Cal. 720 examples; Uhrenkosmos calls the 6210 Cal. 700. Bonhams describes ref. 5056 movement 4215 as a Cal. 700 base reworked into what Rolex called Cal. 720, and Vetroplastica describes the Kew movement as Cal. 700-based with Cal. 720 parts. These are source-specific labels for manual Kew A movements. The generic Cal. 720 entry above describes the automatic branch. Bonhams, ref. 5056 Christie’s, ref. 6210 Bonhams, ref. 6210 Vetroplastica Uhrenkosmos

White’s reference table also maps ref. 6031 to Cal. 710, but the auction records describe automatic date watches. Antiquorum’s 2001 lot and 2002 lot list 10½ lignes and 19 jewels without naming a caliber; the latter combines refs. 6031 and 6074. Phillips records movement G3569, and Sotheby’s G9307, but neither names a caliber. The assignment remains unresolved.

Antiquorum describes ref. 2280 with a 10½-ligne, 17-jewel lever movement, Superbalance and self-compensating Breguet spring. Sotheby’s lists a 10½-size, 17-jewel movement for case 217’903 and a mechanical 17-jewel movement for case 123’375, without a size or caliber number. Watch LIFE News assigns Cal. 710 to its pictured ref. 2280. The image shows the watch but no movement view, so the caliber remains a source attribution for that example; auction catalogues describe others by jewel count or movement size. Antiquorum, ref. 2280, lot 466 Sotheby’s, lot 8042 Sotheby’s, lot 403 Watch LIFE News, 2022 Bonhams 2012 lot 127 via EveryWatch, ref. 2280, case 79,895

Toovey’s photograph of ref. 2318, case 033015, shows a hand-wound movement marked “15 RUBIES.” Other listings give 15 jewels, and WatchNet reports 10¾ lignes for its example. None of the reviewed descriptions names a numbered caliber. Toovey’s Bold Timepieces Vintage Watch Centre WatchNet

Auction catalogues describe compatible 10- to 10½-ligne manual movements in 2765, 2595 and 3009, but none of the surfaced records shows a Cal. 700 stamp. All three reference pages therefore treat the assignment as plausible rather than confirmed. The eight catalogue entries for 1873 identify manual movements with 15–18 jewels and Extra Prima or Ultra Prima grades; the entries give no caliber designation.

Christie’s catalogues identify 18-jewel Ultra Prima chronometers timed to six positions in ref. 2942 examples. Waecce describes the photographed movement as a 10½-line Hunter; these details support an Ultra Prima listing without a numbered-caliber assignment. Christie’s, case 30,125 Christie’s, 2000 lot 715 Waecce Watches

Two Antiquorum catalogues from 1989 describe ref. 3003 and 3004 movements as 10-line, 15- and 17-jewel examples respectively. Neither entry names a caliber. These lot descriptions do not confirm Cal. 700 or 710 fitment in either reference.

6244 is the one reference in this group with a confirmed caliber stamp: Bonhams, Antiquorum, Christie's and Phillips all independently name Cal. 710 across watches spanning both of the reference's numeric case-serial bands. One Christie's catalogue instead describes the movement only by size, "Calibre 10¾," without giving the caliber number.

Watches of Knightsbridge catalogues a circa-1952 ref. 6056 with a 17-jewel manual-wind Cal. 710. Eguchi Vintage lists a separate seller-identified 6056 with partial serial 863*** and also names manual Cal. 710. Neither source provides a movement photograph; Eguchi says its movement was checked only. These are individual catalogue attributions, not verified reference-wide fitment. Watches of Knightsbridge, 19 November 2016, lot 328; Eguchi Vintage, ref. 6056 listing

Two auction catalogues also assign manual Cal. 710 to ref. 4364: Dorotheum names it for movement 19229 in a circa-1950 watch, and Meeting Art names it for movement E66008 in case 554633. The second listing is mirrored by Gazette Drouot. These are catalogue attributions to two watches; neither provides a readable movement photograph, so keep the caliber assignment lot-specific. Dorotheum, 30 April 2026; Meeting Art, 17 May 2025, lot 30

Cal. 600

Cal. 600, manual, Super Balance — EmmyWatch

detail	value
type	Manual
jewels	17
frequency	Not recorded
power reserve	Not recorded
size	9¾ lignes (Sotheby’s description)
escapement	Not specified in the cited lot
balance	Patented Super Balance
regulator	Not specified in the cited lot
shock	None documented

Cal. 600 sits one size class below the 10½-ligne 700/710/720 family and carries a patented Super Balance. Sotheby's describes the movement in the Mercedes Gleitze Oyster, No. 34075 as a rhodium-finished 9¾-ligne Hunter upgraded to Cal. 600, with 17 jewels. The catalogue records an upgrade but gives no date for it. Christie's calls the same watch Oyster Precision, No. 34075; Sotheby's describes it as a pre-production prototype and reports Glasgow marks for 1926/1927. The caseback inscription names the Vindication Channel Swim of 21 October 1927. These details identify the individual watch, not a reference-wide Cal. 600 fitment.

Master of Time separately describes one Viceroy ref. 1573 as an Extra Prima Cal. 600 with 17 jewels and six adjustments. That is a dealer attribution to one watch, not evidence of reference-wide fitment. The Gleitze watch also came with a mid-1970s Rolex service box, but Sotheby's presents its association with a particular service as an assumption; the box does not date the movement upgrade.

The cited Sotheby’s description does not specify the escapement, regulator or shock protection. Those details need examination of the movement.

Cal. 59

detail	value
type	Manual
jewels	15 or 17
frequency	Not recorded
size	10½ lignes (Fontainemelon FHF 30 ébauche)
escapement	Straight-line lever
balance	Monometallic
regulator	Not specified in the cited lots
shock	None documented

The 10½-ligne FHF 30 was made by Fontainemelon. David Boettcher documents it in Oyster Watch Co. watches and identifies Cal. 59, with a centre-seconds 59SC version, as Tudor designations. That account does not establish a Rolex factory designation for Cal. 59. Auction catalogues use the name for individual watches: four ref. 3478s, one 3121 Grenfell (case 43,475, 17 jewels), and two ref. 3136s. The 3121 record's structured year says circa 1938, while its notes call it a 1940s watch and attribute 1938 to the caseback. Heritage calls the FHF 30 in 3136 case 105063 “subsequently renamed Rolex caliber 59”; Waddington's labels case 147396 Cal. 59. Those are attributions in the named lot records, not proof of universal fitment or a factory naming rule.

Ref. 3351 adds further lot-level attributions. Heritage describes Cal. 59 in Regent case 118141; Dawsons names it in a Lincoln with serial 170648; and Wanna Buy A Watch lists it in a Standard with a masked serial. AntiWatchman's separate Regent photograph shows a movement marked 59. Darlor also lists Cal. 59 on a dealer-described 3351-F with serial 118,489. Christie's records an Extra Prima in another 3351 Extra Precision. These are attributions to individual watches, not one movement specification for the reference. (Heritage; Dawsons; Wanna Buy A Watch; AntiWatchman; Darlor; Christie's) Cal. 700/710 assignments below remain family-level matches rather than photographed or catalogued stamps.

Jewel count splits 15 and 17 across the four directly-named 3478 watches; the cited 3136 lots give 15 jewels. The 3478 sample does not track cleanly with any other documented variable. 2784 carries the same family attribution, but only at the family level: no auction catalogue names Cal. 59 outright for that reference, and the one movement image tied to a visibly stamped 2784 case has a Tudor-signed bridge that may be a later replacement.

Cal. A260

Cal. A260-era movement, engraved Rolex Self Winder, Jewels, Patented

detail	value
type	Automatic
jewels	19
frequency	18,000 vph (2.5 Hz)
power reserve	36h
size	26.4mm
escapement	Straight-line lever
balance	Superbalance, blued Breguet spring
shock	Present (unnamed brand)

A260 powered the first Submariner references, 6204 and 6205, from 1953 to 1955. "A.260" is Rolex's size-family code for this movement class, comparable to the Prince family's "T.S." code. Its non-butterfly rotor distinguishes it from the butterfly-rotor Cal. 1030. Hodinkee traces A260 to a movement used in earlier Oyster Perpetuals and later Bubblebacks, predating its Submariner fitment. The registry uses 17 jewels; some auction descriptions give 19, so the count should be checked against the individual movement. Auction catalogues use both labels on ref. 6106 examples: Monaco Legend identifies case 803400 as A260, while Antiquorum names Cal. 645 in a separate 6106. These are specimen-level attributions, consistent with A.260 as a size-family code rather than a unique commercial caliber name.

Cal. A296

Cal. A296-era rotor component, engraved Rolex Perpetual Chronometer

detail	value
type	Automatic
jewels	17 (registry; 18–19 in catalogues, depending on module counting)
frequency	18,000 vph (2.5 Hz)
power reserve	36h
size	29.5mm
escapement	Straight-line lever
balance	Monometallic Superbalance
regulator	Index
shock	Shock absorber (775-labelled lots only)

Catalogues place A296 in the early 1950s, with the registry using a working window of 1953–1956. It powered the Big Crown 6200, early Explorers 6098, 6150 "Precision," 6298, and 6350, and early Datejusts 6104 and 6105. Phillips also identifies A.296 in one 6075, case 714440; other auction catalogues name A.295 in 6075 cases. That conflict is attached to the reference page rather than treated as a universal movement rule. Its full rotor winds in one direction; it is not a bumper caliber. The 6150 and 6350 use related movements in non-chronometer and chronometer-rated watches. COSC itself was founded later, in 1973. "A.296" is Rolex's size-family code and 775 its commercial number, so listings may use either designation for the same movement. Cal. 1030 replaced it in the mid-1950s with bidirectional winding, a butterfly rotor, and a thinner automatic module. Phillips identifies that reduced thickness as the change that eliminated the domed Bubbleback caseback.

The movement has a straight-line lever escapement, monometallic balance, self-compensating Breguet balance spring, and index regulator. Catalogues using the commercial number 775 also specify six-position adjustment and a shock absorber. A.296 is a broader designation than a unique caliber stamp; catalogue usage needs checking against the individual movement.

Christie's describes a 6150 balance as a "patented Super-balance," linking it to Aegler patent CH196706 and the recessed timing screws used on Cal. 300. Published jewel counts vary because some catalogues separate the going train from the automatic module. Figures of 18 and 19 appear for the base movement, with another two or seven assigned to the rotor module. One 6150 is described as a 19-jewel movement with a two-jewel automatic module. A bare jewel total in a reference table does not reveal which components were counted.

Cal. 645

Cal. 645 winding bridge, engraved "Rolex Perpetual Chronometer, Super-Balance, Patented" — EmmyWatch

detail	value
type	Automatic
jewels	17–20
frequency	18,000 vph (2.5 Hz)
power reserve	41h
size	26.4mm
escapement	Straight-line lever
balance	Superbalance, timed to 6 positions
regulator	Index
shock	Shock absorber

Cal. 645 belongs to the Cal. 600 family and shares the A.260 size code with Cal. 635. The distinctions are functional: Cal. 630 has sweep seconds without shock protection, Cal. 635 has small seconds with shock protection, and Cal. 645 combines sweep seconds with shock protection. Cal. 645 powered the semi-Bubbleback Oyster Perpetual refs 6084, 6085, and 6284 around 1948–1953. Hodinkee's listing for ref. 6108 case 803948 identifies Cal. 645. Antike Uhren Eder's 1952 listing for ref. 6108, item 7140rol, also identifies Cal. 645; it gives no case or serial number, so its identity relative to the other listed watches cannot be checked. Heritage's 2012 lot for case 803'752 lists the movement as F 64550, with no caliber designation. Auction catalogues give 17 to 20 jewels, consistent with both differing counting conventions and market-specific tariff variants found elsewhere in the family.

Catalogue labels for ref. 6085 do not agree. Hodinkee Shop and a second dealer listing call their examples A260; Christie’s, Phillips, Schmitt-Horan, and Dorotheum identify Cal. 645 in theirs. Since A.260 is a size-family code rather than a unique commercial caliber name, keep each label tied to its listing unless the movement itself can be checked.

The movement uses a straight-line lever escapement, Superbalance adjusted to six positions, shock absorber, self-compensating Breguet balance spring, and index regulator. Some catalogues use "monometallic balance timed to 6 positions" instead of Superbalance. Both terms describe a monometallic balance with recessed timing screws.

Watch Doctor’s chart groups Cal. 635 and 645 under A.260 and assigns both to 1950. That online entry is not an identified factory production record.

Antiquorum catalogued a subsidiary-seconds ref. 3599 as Cal. 635 with 19 jewels and described the caliber as 9¾ ligne, made from 1940 to 1951. The catalogue’s 1940–1951 span differs from Watch Doctor’s 1950 entry. Christie's also catalogued a visibly centre-seconds 3599 as Cal. 635, which conflicts with the caliber's small-seconds architecture. Without movement photographs, the Christie's caliber entry is best treated as a catalogue error rather than evidence for a centre-seconds Cal. 635.

Jewel counts also vary according to whether a catalogue includes the automatic module. Bonhams describes the related Cal. 745 as "18 jewels plus 7 rotor jewels." Its 20-jewel description of a Cal. 645 in a 6085 should remain attached to that example; it does not establish a universal jewel count.

Cal. 720 (automatic lot attribution)

detail	value
type	Automatic, as catalogued in one ref. 5026
jewels	18, according to Aste Bolaffi lot 4
other specifications	Not recorded in the source
evidence	Case 443371; no movement photograph

Aste Bolaffi identifies an automatic Cal. 720 with 18 jewels in ref. 5026, case 443371, dated circa 1958. This is one catalogue attribution; the lot has no movement photograph, and the other exact-reference records located do not name a caliber. Keep this use separate from the hand-wound Kew A reports that also use “Cal. 720” for a Cal. 700-based movement or components. Aste Bolaffi, lot 4 Bonhams, ref. 5056 Vetroplastica

Cal. 740

Cal. 740 in a reference 4467 Datejust, case back removed, rotor engraved "Rolex Perpetual Chronometer, Super Balance, Vis Tirette"

detail	value
type	Automatic
jewels	26 in the cited Antiquorum lot
frequency	18,000 vph (2.5 Hz)
power reserve	Not recorded
size	10½ lignes in the cited catalogue
escapement	Straight-line lever
balance	Superbalance, adjusted to 6 positions
regulator	Not specified in the cited 740 lot
shock	Not named in 740 lot text

Antiquorum catalogues Cal. 740 in a Datejust ref. 4467 with a date display. Its Geneva 2002 lot 486 describes the reference as produced from 1945 to 1949. The catalogue supports the caliber identification in that watch; it does not establish the exact introduction date of every movement fitted during the reference's run.

The 10½-ligne rhodium-plated movement has a straight-line lever escapement, Superbalance adjusted to six positions, and self-compensating Breguet balance spring. Some catalogues substitute "monometallic balance adjusted to 6 positions" for Superbalance, as they do for Cal. 645. No Cal. 740 description names the regulator. Antiquorum describes an index regulator on its A.295-attributed ref. 6075, case 714441 ([2014 lot 107](https://catalog.antiquorum.swiss/en/lots/rolex-ref-6075-lot-283-107)); that is a separate catalogue attribution, not evidence that A.295 and Cal. 740 are interchangeable names.

Antiquorum gives 26 jewels for its Cal. 740 example. That count should be kept with the source's description. A different count in a reference table may reflect a counting convention or a different execution; the number alone does not settle which.

Antiquorum also assigns Cal. 740 to manual-wind ref. 6094, usually with 17 jewels. Its 2008 lot labels the case 6094/6294; the 2010 and 2012 lots identify ref. 6094 alone. The 2018 listing for case 882812 calls the watch self-winding in its headline while the specification field gives Cal. 740. Watch-Wiki lists Cal. 740 as an automatic 18-jewel Datejust movement; Antiquorum describes the ref. 4467 Cal. 740 documented here as automatic with 26 jewels. These records use Cal. 740 for different movement descriptions. A separate 6094 photograph shows Rolex and 17 jewels, but no legible caliber stamp; it cannot confirm the auction attribution. Antiquorum, lot 530; Antiquorum, lot 134; Antiquorum, lot 291; Antiquorum, lot 138; EveryWatch transcription of Bonhams, lot 85; HASHTAGWATCHCO, ref. 6094 listing photographs; Watch-Wiki, Rolex calibre index.

Surviving examples can have replacement movements or parts. A reference launch date should not be assigned automatically to the movement now inside a particular case.

The cited Cal. 740 lot does not identify a shock-protection system or regulator. Inspect those components rather than infer them from silence in a catalogue.

Cal. A.295 in Datejust auction records

Antiquorum identifies ref. 6075 case 714441 as A.295, with a 10½-ligne movement, 19 jewels and an index regulator ([2014 lot 107](https://catalog.antiquorum.swiss/en/lots/rolex-ref-6075-lot-283-107)). Christie's also calls a circa-1950 ref. 6075 A.295 ([case 699455](https://www.christies.com/en/lot/lot-6042730)). Phillips, however, identifies ref. 6075 case 714440 as A.296 ([2015 lot 284](https://www.phillips.com/detail/rolex/CH080515/284)). The catalogues do not establish whether this reflects a production change, differing usage or a later movement. Check the actual stamp before assigning a caliber.

Keep this A.295 attribution separate from A.295 CPL, the complete calendar and moonphase movement catalogued in ref. 8171.

Ref. 5029 catalogue descriptions also differ: Hodinkee calls case 610727 A.295, while Phillips calls case 651'517 “Automatic, Super Balance, 730.” Antiquorum describes 9¾-line, 18-jewel movements in cases 673206 and 660596 without a caliber number. The lots do not include movement photographs for those cases, so these labels remain example-specific; the evidence does not support a new caliber entry or a 5029-wide assignment. Hodinkee Phillips Antiquorum, lot 295 Antiquorum, lot 433

Cal. 745

Cal. 745, gilt rotor engraved "Rolex Perpetual Chronometer, Super Balance" — EmmyWatch

detail	value
type	Automatic
jewels	18 + 7 rotor
frequency	18,000 vph (2.5 Hz)
power reserve	42h
size	29.5mm
escapement	Straight-line lever
balance	Superbalance
regulator	Index
shock	Shock absorber

Cal. 745 is an automatic calendar movement used in early Datejust references. Cal. 740 is also catalogued with a date display, so the calendar alone does not distinguish the two calibers.

Bonhams describes a Cal. 745 in a ref. 6305 as rhodium-plated, with 18 jewels plus seven rotor jewels, a straight-line lever escapement, Superbalance, shock absorber, self-compensating blued-steel Breguet balance spring, and index regulator. Eighteen base-movement jewels plus seven rotor jewels gives 25. That arithmetic does not explain a catalogue count of 26; compare the actual movement before treating the descriptions as equivalent.

Cal. 745 appears in the Datejust "Ovettone" group. Documented examples include a circa 1955 18K yellow-gold ref. 6305, case 97602; a ref. 6105 with 1952 Glasgow import marks and movement H78230; and a circa 1955 ref. 6304 with movement 99698/H46452. Other ref. 6105 examples use A296, placing the reference across the boundary between the A.295 and A.296 groups. The claimed Cal. 745 fitment in ref. 6039 is unverified; no supporting lot description or confirmed Rolex ref. 6039 has been identified.

Calendar and moonphase

Cal. A.295 CPL

Detail	Value
Type	Automatic complete calendar with moonphase
Size	10½ lignes
Jewels	18 in the cited examples
Seconds	Subsidiary seconds at 6, sharing the moonphase subdial
Reference	8171 Padellone

Auction catalogues call the 8171 movement A.295 CPL, A295 or simply 10½ lignes. Day and month appear in windows; a central pointer reads the outer date scale. Four recessed correctors adjust month (near 2), date (near 4), moonphase (near 8) and weekday (near 10). Christie’s, 8171 case 685878; Giorgia Mondani, 2020

The contemporary 6062 uses a different movement. Christie’s catalogues its 6062 case 916321 with caliber 655. Matching calendar displays do not establish interchangeable calibers. Christie’s, 6062 case 916321

Oyster and Oysterdate Precision

Precision is Rolex's non-chronometer manual line, a 10½-ligne family built alongside the automatic Bubblebacks. The Oysterdate Precision 6694 remained in production through the end of the 1980s, a year beyond the hand-wound Daytona; one surviving lot includes a 1990/1991 Rolex calendar card. Rolex continued making manual-wind watches after the 6694: the Cellini Danaos used Cal. 1602 into 2008, and the chronometer-certified Cellini Prince used Cal. 7040 until about 2015. The small-seconds Cal. 1240 also carried this architecture into the platinum Cellinium 5240 and 5241. Seconds placement, date and beat rate distinguish the seven commercial numbers. Rolex's parts plates identify Cal. 1210 as the base for 1200, 1215, 1220, 1225 and 1240.

Cal. 1210

Cal. 1210 in a 1960 Oysterdate Precision ref. 6466, movement in case

detail	value
type	Manual
jewels	18 (factory plate) · 17 (as signed and catalogued)
frequency	18,000 vph (2.5 Hz)
power reserve	~58h
size	10½′′′ / Ø23.80mm × 4.27mm height
escapement	Straight-line lever, jewelled pallet fork
balance	Glucydur, screwed rim, Breguet overcoil
regulator	Index with movable stud support
shock	KIF-pattern on documented later examples; earliest examples may lack protection

Rolex's parts plates identify Cal. 1210 as the family's architectural base and file the small-seconds 1200 as a derivative. The parts plates support Horbiter's identification of Cal. 1210 as the base; Fratello names Cal. 1200.

The jewel count remains unclear. Rolex specifies 18 jewels for the two no-date calibers and 17 for the date versions, yet known movements are signed "Seventeen Jewels" and major-house catalogues consistently give 17. Both counts are documented, but their distribution among watches has not been established. Contemporary American import duties taxed jewel count and also account for the "UNADJUSTED" stamps found on some movements.

The balance is Glucydur with a Breguet overcoil, as specified on the sibling Cal. 1200 plate. Regulation uses a conventional index and movable stud, with adjusting washers in five thicknesses. It is not free-sprung; Rolex reserved Microstella for its 12½-ligne chronometers.

The pallet fork runs in jewels, while the escape wheel has shock-mounted settings and cap jewels on both pivots, matching the treatment of the balance. Indirect centre seconds, driven from the fourth wheel through a friction-sprung pinion, can produce seconds-hand flutter even in a healthy movement. The earliest examples may lack shock protection; Antiquorum's 1946 ref. 4560 description names none.

Documented fitments include refs. 3745, 4560, 6420, 6422, 6426/6427, 6466, 6480, 6482, 6494, 9083 and 9659. Bonhams also records a ref. 6694 with a III.60 caseback date on Cal. 1210. Vintage Watch Centre also assigns Cal. 1210 to its ref. 4219, case 056827, but no caliber engraving is visible in the movement photo. The dealer dates the case circa 1948; White's Field Manual lists Cal. 1210 as 1954–1964 on PDF page 91. These conflicting attributions remain tied to that one watch. The 4219 article records the discrepancy. Vintage Watch Centre; The Vintage Rolex Field Manual, PDF p. 91.

Auction catalogues identify Cal. 1210 in ref. 8952 examples dated circa 1955 and 1956. Phillips also assigns Cal. 1210 to a ref. 8952 dated circa 1945, earlier than the Field Manual’s 1954–1964 range. Keep that date/caliber pair as an unresolved lot attribution. The 8952 article records the examples and date conflict. Sotheby’s, lot 263; Monaco Legend, lot 57; Phillips, lot 1037; The Vintage Rolex Field Manual, p. 91.

Cal. 1215

Cal. 1215 in a movement holder, from a 1962 Oyster Date Precision ref. 6694 service

detail	value
type	Manual
jewels	17
frequency	18,000 vph (2.5 Hz)
power reserve	~58h
size	10½′′′ / Ø23.80mm × 5.07mm height
escapement	Straight-line lever
balance	Glucydur, Breguet overcoil (via base 1210) · flat in one lot
regulator	Index with movable stud support
shock	KIF-pattern
date	Non-quickset, dragging change

Cal. 1215 adds a calendar to the 1210, increasing movement height from 4.27mm to 5.07mm. Its two-page parts sheet covers only the calendar mechanism and defers the rest to Cal. 1210. Date discs came in champagne, silvered, and champagne with red-and-black printing.

The hairspring is disputed. The parts plates imply the 1210's Breguet overcoil because the 1215 sheet specifies no separate balance. Antiquorum describes one ref. 9996 with a flat hairspring and index regulator, but uses Breguet wording elsewhere. No catalogue describes the caliber as free-sprung.

Cal. 1215 uses a gradual date change rather than a direct quickset. The date begins moving before midnight and seats as the mechanism completes its cycle.

Christie's places the ref. 6494 changeover between a circa-1956 example with Cal. 1210 and a circa-1958 example with 1215. Other documented fitments include the Speedking 6430, early 6694 production, and refs. 9996/9919.

Cal. 1216

detail	value
type	Manual (assumed, by family)
jewels	not documented
status	Number attested in the parts trade only

Almost nothing is known about Cal. 1216. The common description of it as a 17-jewel Cal. 1215 variant has no traceable support.

Rolex's surviving parts plates cover 1200, 1210, 1215, 1220, 1225 and 1240, but omit 1216. No major-house lot identifies a Rolex Cal. 1216, and Heritage's apparent example is a case reference. Confusion is also possible with Ronda's contemporary 1216 movement.

The parts trade nevertheless records it as a Rolex number. Cas-Ker's genuine-parts catalogue places 1216 between 1215 and 1220 and lists crown-wheel screw 1216.5420, following Rolex's caliber-prefixed numbering convention.

The parts catalogue attests the Cal. 1216 designation. Its jewel count, seconds layout, beat rate and fitments remain unknown. Published specifications derived from the 1215 are unconfirmed.

Cal. 1220

detail	value
type	Manual
jewels	18 (factory plate) · 17 (as signed)
frequency	21,600 vph (3 Hz)
power reserve	~58h
size	10½′′′ / Ø23.80mm × 4.27mm height
escapement	Straight-line lever
balance	Screwless, inertia blocks, flat hairspring
regulator	Index with movable stud support
shock	KIF-pattern

Cal. 1220 raises the 1210 platform to 21,600 vph and uses a different oscillator. Both its parts plate and the 1978 third edition of Rolex's Technical and Service Information give that rate. The sometimes-published 19,800 vph figure is unsupported.

The higher-beat generation replaces the 1210's screwed Glucydur balance and Breguet overcoil with a smooth-rimmed balance and flat hairspring. Gilt and nickel-plated inertia blocks provide about ten seconds per day of fine adjustment across their range; the index handles larger corrections. Separate regulator, stud-support and regulating-stud parts confirm that this is an index-regulated movement, not a free-sprung one.

Cal. 1220 appears mainly in the oversize ref. 8029, but its dates conflict. Phillips gives 1950, Antiquorum dates case 714105 to about 1951, and Sotheby's dates that same case to about 1961 without naming its caliber. The earlier dates sit awkwardly beside the later-1960s siblings and remain unresolved. Phillips identifies a late ref. 6426 movement as RB 1225. That catalogue supports the marking on this watch; whether it began as a Cal. 1220 and was re-marked has not been established.

Cal. 1225

Cal. 1225 in a ref. 6694 Oysterdate Precision, bridges marked "Montres Rolex S.A. Swiss"

detail	value
type	Manual
jewels	17
frequency	21,600 vph (3 Hz)
power reserve	~58h
size	10½′′′ / Ø23.80mm × 5.07mm height
escapement	Straight-line lever
balance	Screwless, inertia blocks, flat hairspring
regulator	Index with movable stud support
shock	KIF
date	Non-quickset, dragging change

Cal. 1225 adds a calendar to the 1220 and carried the Oysterdate Precision 6694 through its final years. Rolex's plate specifies a timed flat hairspring with gilt and nickel-plated inertia blocks, consistent with Antiquorum's descriptions of refs. 6426 and 6694. Published claims of a Breguet overcoil conflict with the factory plate and auction record. Bonhams' reference to a "Gyromax balance" is a cataloguing error; Gyromax is Patek Philippe's free-sprung system.

Rolex used "Precision" on uncertified manual and automatic movements, including the Air-King 5500. On Cal. 1225, the "UNADJUSTED" stamp records an import-duty classification.

The caliber does not hack. The 1210 parts plate contains no stop lever or hack spring, and Rolex's 1978 service book covers hacking only for the late 1500 series and the 2030/2035.

For an Oysterdate Precision with Cal. 1225, service requirements depend on the condition of the individual watch. Rolex’s published procedure begins with a watchmaker’s examination and an estimate. It does not promise routine acceptance of every vintage caliber or a particular rate and power reserve after service.

Documented fitments include ref. 6426, 6466 and, most often, 6694 from the late 1960s through at least 1979. Comparison of a 1966 ref. 6694 with Cal. 1215 and a 1973 example with 1225 places the changeover around 1967.

Cal. 1200

Cal. 1200, bridges marked "Montres Rolex S.A. Geneva Swiss, Seventeen 17 Jewels", from a Rolex Precision service

detail	value
type	Manual
jewels	17
frequency	18,000 vph (2.5 Hz)
power reserve	~58h
size	10½′′′ / Ø23.80mm × 3.65mm height
escapement	Straight-line lever, jewelled pallet fork and staff
balance	Glucydur, Breguet overcoil
regulator	Index with movable stud support
shock	"Rolex Shockresisting" device

Cal. 1200 is the family's small-seconds variant and, at 3.65mm, its thinnest member. Moving the seconds from the centre to a subdial requires a separate main plate and train-wheel bridge rather than an added module. The plate, bridge, third and fourth wheels, pallet fork and staff are jewelled.

The bilingual parts plate specifies Rolex's own "Shockresisting" device rather than a trade name. It lists a pivoted Glucydur balance with roller and a regulated Glucydur balance with Breguet hairspring, the 18,000-vph oscillator inherited by the 1210 and 1215.

The caliber number is engraved in the balance-wheel hub sinking rather than on a bridge or the main plate. The same document directs watchmakers to Cal. 1210 for all shared parts, confirming the family's parentage.

No major-house lot names Cal. 1200, so its fitments remain unestablished. The high-beat small-seconds Cal. 1240 is better documented in the platinum Cellinium 5240 and 5241, with a monometallic balance adjusted to four positions and a flat hairspring. That caliber kept the architecture in production for about a decade after the Oysterdate ended.

Vintage sport calibers (Submariner, GMT-Master, Explorer, Air-King)

The A-series and Cal. 1030 preceded the long-running 15xx family. Cal. 1520 became its main uncertified movement, while Cals. 1560 and 1570 supplied chronometer-rated sport references into the 1980s.

Cal. 1030

Cal. 1030, engraved "1030," 25 jewels, butterfly rotor

detail	value
type	Automatic
jewels	25
frequency	18,000 vph (2.5 Hz)
power reserve	42h
size	28.5mm × 5.85mm
escapement	Straight-line lever
balance	Monometallic, blued Breguet spring
shock	KIF

Cal. 1030 is a bidirectionally wound automatic used in 1950s Oyster references. Its 5.85mm profile ended the domed Bubbleback caseback, while the cutaway "butterfly" rotor stamped ROLEX PERPETUAL PATENTED is the usual visual identifier. Finishing includes perlage on the rhodium-plated main plate, brushed bridges, polished screw heads and red anodized-aluminium reversing wheels. A conventional index regulates the movement; the visible regulator arm distinguishes it from the later free-sprung 1560 and 1570. Documented fitments include ref. 6098 from 1952, Oyster Perpetual 6502, 6567 and 6584, Submariners 6536, 6536-1 and 6538, Explorer 6610 and Air-King 6552. Artcurial, Antiquorum and Sotheby’s catalogue 6502 examples with Cal. 1030; Watch-Wiki independently lists the association. The case 36701 records conflict: the Invaluable archive of Monaco Legend labels it 6502, while Phillips identifies that case as 6603. The competing catalogue attributions leave its reference unresolved. Invaluable archive of Monaco Legend, lot 166; Phillips, lot 254 Freeman’s and EBTH catalogue Cal. 1030 in gold ref. 6584 watches (Freeman’s, lot 2; EBTH, item ITMG535812). Artcurial’s archived catalogue assigns it to a steel 6584, and Antiquorum to a jointly listed 6080/6584 (Artcurial archive, lot 870; Antiquorum, lot 133). These are lot-level attributions. The Field Manual and several auction catalogues identify Cal. 1030 in Oyster Perpetual 6567 examples; Ineichen lists Cal. 1050 for one 6567. Other catalogues assign Cal. 1050 to refs. 6564, 6569 and Submariner 6536/1. These are descriptions of individual watches; the Cal. 1050 entry records the competing attributions.

Cal. 1035

Cal. 1035, rotor engraved "Rolex Perpetual Patented" — EmmyWatch

detail	value
type	Automatic
jewels	25
frequency	18,000 vph (2.5 Hz)
power reserve	42h
size	28.5mm × 6.66mm
escapement	Straight-line lever
balance	Monometallic, temp + 5 positions
regulator	Index (Cal. 1030 base)
shock	Shock absorber

Cal. 1035 adds a date to the 1030 and appeared in 1957. Documented fitments include Oyster Perpetual Date refs. 6518, 6530 and 6534. Auction catalogues for ref. 6609 name Cal. 1065 or 1066; Phillips lot 118 lists Cal. 1030. Rolex describes the 1035's non-quickset calendar as "progressive": the date moves gradually through the night, unlike the instant-change 1036 GMT.

The 1035 inherits the 1030's conventional index regulator. Although auction descriptions do not name the regulator, the production dates and shared base support the index arrangement.

Rolex stamped the 1035's self-winding bridge "1030," as it also did on the 1036. This causes auction catalogues to identify the same reference under both numbers. The calendar work and 6.66mm height distinguish the 1035 from the 5.85mm no-date 1030. A correct ref. 6534 contains a 1035 regardless of its bridge engraving.

Cal. 1040

detail	value
type	Automatic
jewels	26 in examined catalogue descriptions
function	Dead-beat centre seconds
base	Modified Cal. 1030 architecture
documented fitment	Oyster Perpetual Tru-Beat ref. 6556

Cal. 1040 powers the Oyster Perpetual Tru-Beat 6556. Its centre seconds hand pauses at each marker and advances once per second. Christie’s calls it a modified Cal. 1030; watchmaker Aaron Berlow’s account of a single restoration identifies a longer second intermediate wheel for the dead-beat mechanism. His report supports the relationship between the two calibres, but does not establish that every 1030 part is interchangeable.

Christie’s, Phillips and Antiquorum catalogue 26 jewels on the examined examples. Phillips also catalogues one watch as ref. 6558 with an inner caseback stamped 6556 and Cal. 1040; that lot does not establish general 6558 fitment. The available records do not establish a changeover sequence, beat rate, power reserve, or full production interval for the 1040. Auction essays place the 6556 introduction in 1954 and often give 1959 as its end; later-dated 6556 lots make the cutoff uncertain. Those dates describe the watch reference and should not be treated as a verified movement production range.

Hodinkee’s 2016 review says the dead-beat function was often removed during service, though the photographed example still worked. Watchmaker Aaron Berlow wrote in 2015 that reports of Rolex replacing the 1040 module with 1030 parts were internet hearsay he had not seen first-hand. These accounts do not establish a service frequency or document a specific replaced movement.

The literature on the 6556’s proposed successor describes 1020 inconsistently. Antiquorum’s 2012 catalogue and Dr. Crott’s 2019 listing call it a new reference intended to replace the 6556, and say it was never produced. Crott’s 2012 catalogue instead calls 1020 a new caliber. White’s The Vintage Rolex Field Manual lists ref. 1020 with Cal. 1560, a smooth bezel, and a full-size case, but supplies no example or source for that row. The 1960 Rolex catalogue is not reproduced in these records, so they do not establish whether 1020 was only a plan or also identifies a separate Oyster Perpetual, or which movement it would have used.

Cal. 1050

detail	value
type	Automatic, as described in the cited catalogues
jewels	25 in the Antiquorum 6564, Bonhams 6569, and Christie's 6536/1 descriptions
catalogue attributions	Oyster Perpetual refs. 6564, 6567 and 6569; Submariner ref. 6536/1

Several auction catalogues identify Cal. 1050 in watches dated to the 1950s. Antiquorum names it in a ref. 6564; Bonhams in a ref. 6569; Christie's in a Submariner 6536/1; and Ineichen in a ref. 6567. The 6564 and 6567 also appear in records naming Cal. 1030. These are catalogued assignments to individual watches. Cal. 1050’s technical relationship to Cal. 1030 and any changeover sequence remain unresolved. Antiquorum, ref. 6564, lot 114 Bonhams, ref. 6569, lot 312 Christie's, Submariner ref. 6536/1 Ineichen, ref. 6567, lot 4

Cal. 1530

Cal. 1530-era butterfly rotor halves, Rolex coronet stamped

detail	value
type	Automatic
jewels	17 / 25 / 26 (market variants)
frequency	18,000 vph (2.5 Hz)
power reserve	42h (registry; 44h in some secondary tables)
size	12½′′′
escapement	Swiss lever, club-tooth
balance	Screwed Glucydur
regulator	Index (coarse) + micro-star fine-adjust screws
shock	KIF, form-dependent (Flector or Elastor)

Cal. 1530 ran from 1957 to 1965. Its 17-, 25- and 26-jewel versions are concurrent market variants, not a chronological progression. Seventeen-jewel movements appear in a 1958-era ref. 5508 and a 5500, and Rolex’s Technical and Service Information, third edition, discusses the 1520 and 1530 families in its servicing instructions.

Cal. 1530 is the base for the 1520, 1560, 1570 and 1580. They share plates and many service parts, including interchangeable automatic-device bridges, so the engraved bridge number may not identify the movement beneath it. Balance-bridge and regulator form are more reliable.

Regulation combines an index for coarse adjustment with two pairs of micro-star fine-adjustment screws on the outer balance rim. Turning a screw clockwise draws it inward and gains rate. The system resembles Microstella, and Horotec lists the same adjustment tool for the 1530 and later Microstella calibers, but Rolex reserved the Micro-Stella name for its free-sprung 12½-ligne chronometer movements. The 1530 retains an index.

The form-1 balance cock uses KIF Flector; forms 3 and 4 use Elastor, with form 2 also assigned to Flector by specialist comparisons. Interchangeable bridges mean an individual movement's shock setting may not match its engraved caliber number.

The hairspring remains disputed. Antiquorum consistently describes a Breguet overcoil and index regulator, while much of the reference literature gives a flat hairspring with stick regulation. Reliable sources support both descriptions.

Chronometer status also varies. Sotheby's describes the 1530 as uncertified, while Phillips and Christie's identify chronometer examples in the 5504 family. Rare 5512 and 5508 watches with four-line chronometer dials and Cal. 1530 have been reported, though no major-house lot confirms them. Certification appears to have been occasional. The Microstella-equipped 1555 and 1560 became the regular chronometer alternatives used in early refs. 1675 and 1016.

The rotor changed from butterfly to half-moon during production. Later movements also gained blued automatic-bridge screws and coloured reversing wheels in place of brass-coloured gears. Rolex describes the red wheel finish as a hardening treatment for aluminium introduced in 1957; collector descriptions often call the wheels purple and Teflon-coated. Rotor and reversing-wheel form help date an example.

The 1530 first entered the Submariner in ref. 5508, followed by 5510; neither was chronometer-rated at launch. It replaced the 10-series in non-chronometer watches, including Precision models, the Air-King, ref. 5504 "Super-Precision" Explorer and the Canadian Explorer-Date with Cal. 1535. Certified models such as the 6542 GMT, 6610 Explorer, Datejust and Day-Date retained 10xx calibers for longer. Strongly documented fitments include refs. 5508, 5510, 5512, 5513, 5500 and 5504. Single-lot support exists for 5501, 5502, 5506 and 5516. Bonhams listings for refs. 1002 and 1003 are internally inconsistent and remain unconfirmed. Bonhams lot 84 lists caliber 1530 in ref. 1003 case 573,835 and notes a chronometer certificate dated 22 December 1960. The catalogue is the evidence for this individual attribution; it does not resolve why common reference tables omit the 1530 for 1003. Antiquorum’s 1996 Milan catalogue assigns Cal. 1530 to a 14ct Eaton’s watch catalogued as ref. 1011 and dated broadly to the 1950s. Loupe This photos show a 1530-stamped movement in a case marked 5590 on the flank and 5590/1011 inside. Antiquorum’s 2007 and Finarte’s 2024 catalogues also use the combined designation for Eaton’s watches. The 1996 and 2023 records may describe one watch; the 2007 and 2024 lots identify different named or case-numbered examples. Antiquorum’s 2002 catalogue assigns Cal. 1530, with 26 jewels, to one ref. 1014 example (lot 492); see ref. 1014.

Rolex specifies a 0.122–0.125mm mainspring for the 18,000-vph 1530 and 1560, against up to 0.125 or 0.128mm for the higher-beat 1520 and 1570. Early unjewelled barrel-bridge arbor holes can wear; Rolex prescribed closing the hole or reaming it for a jewel, while later production received a bushing. Rotor-axle wear is another known fault. On the 1560, a hard shock could push the hairspring into the regulator. Rolex supplied a safety pin free of charge and later made it standard, so both guarded and unguarded examples are correct.

Cal. 1520

Cal. 1520, engraved "1520," EmmyWatch

detail	value
type	Automatic
jewels	17 / 25 / 26
frequency	19,800 vph (2.8 Hz)
size	12½′′′
escapement	Straight-line lever
balance	Monometallic, screwless, flat hairspring
regulator	Index (coarse) + two inertia blocks
shock	KIF

Produced from 1963 to 1990, Cal. 1520 is the non-chronometer, higher-beat derivative of the 1530. Rolex pairs the 18,000-vph 1530 with the 1560, and the 19,800-vph 1520 with its certified counterpart, the 1570.

Rolex describes regulation by an index and two inertia blocks, one gilt and one nickel-plated, on a screwless balance with a flat hairspring. Turning their splits inward slows the movement and outward gains rate, with about ten seconds per day across the adjustment range. The index handles coarse changes. This differs from both the 1530's micro-star screws and the 1570's free-sprung Microstella system.

Certified calibers use free-sprung Microstella regulation; Cal. 1520 uses an index and inertia blocks.

Rolex’s Technical and Service Information, third edition, describes Cal. 1520’s regulator and inertia blocks. Two Bonhams descriptions call the 1520's balance "free-sprung Gyromax," an error that applies Patek Philippe's trademark to an index-regulated Rolex movement.

Auction descriptions consistently give a flat hairspring, apart from one 2013 Antiquorum outlier that says Breguet. Shock protection is KIF in Flector or Elastor form, identified by balance-bridge and regulator shape. That shape is more reliable than the engraved caliber number because bridges interchange across the series.

The 17-, 25- and 26-jewel counts are concurrent market variants. The 17-jewel version uses a different main plate and bridges, altered escape-wheel pivot geometry, and bushings in place of jewels in the automatic module. Jewel count alone does not establish the rate or condition of an individual movement. Dated examples place 17- and 26-jewel movements together from the mid-1960s, with 25-jewel examples running alongside them.

American tariffs rose sharply above 17 jewels, but Rolex did not document this as the reason for the low-jewel version. Seventeen-jewel movements also reached Europe and Asia, so general cost reduction remains another possibility. The American presentation ref. 7002 has a rotor marked "SEVENTEEN JEWELS" and "UN" for unadjusted, both relevant to the tariff schedule, but this does not settle the question.

Documented fitments include the 5513, 5514 COMEX, 5517 military Submariner, 5500 Air-King and 5520. Ref. 1002 uses chronometer calibers 1530 or 1570; apparent 1520 examples are ref. 5500 cases with 1002 stamped inside the caseback. Ref. 5501 remains unconfirmed. Hacking arrived as a running change around 1972 through parts 8073 and 8074. Two lines above six o'clock identify the non-chronometer dial, against four on certified models.

The barrel bridge and arbor hole are known wear points. Rolex prescribed closing a worn hole or reaming it for a 2.30mm jewel; a later beryllium bushing largely solved the problem. Rotor axles and autowinder wheels also wear, and replacement parts are scarce. Gritty manual winding is normal because the reversers run without lubrication.

Cal. 1535

Cal. 1535, EmmyWatch

detail	value
type	Automatic
jewels	26
frequency	18,000 vph (2.5 Hz)
power reserve	42h
size	28.5mm
escapement	Swiss lever
balance	Monometallic, screwed
regulator	Index, pre-Microstella
shock	Shock-absorber

Cal. 1535 is the non-chronometer date version of the 1530, introduced in 1957 for the Air-King-Date 5700/5701. Monochrome likewise assigns both calibers to the 5700, with 1535 first.

Auction houses usually catalogue refs. 5700 and 5701 under the base caliber. Antiquorum assigns a 1963 ref. 5700 to Cal. 1530 and a 1972 example to 1520, though neither base movement has a date. Those entries agree with Rolex's grouping of 1535 components under Cal. 1530 and 1525 components under Cal. 1520, but they do not identify the fitted caliber.

No auction lot identifies a Cal. 1535 directly, so the listed mechanical figures come from its Cal. 1530 base. Evidence for the hairspring conflicts: auction wording gives a flat spring, while Rolex balance assembly 7855 for the 1530 uses a Breguet overcoil. Repeated catalogue boilerplate is more likely than a separate variant. The 1535 predates Microstella and uses an index with a screwed balance, consistent with the 5700's Precision grade.

Although Cal. 1530 was phased out by 1965, its 1535 date derivative remained in the Air-King-Date into the late 1980s.

Cal. 1525

Cal. 1525, EmmyWatch

detail	value
type	Automatic
jewels	17 / 25
frequency	19,800 vph (2.8 Hz)
power reserve	42h
size	28.5mm
escapement	Swiss lever
balance	Monometallic, flat hairspring
regulator	Index
shock	Shock-absorber

Cal. 1525 is the higher-beat, non-chronometer date version of the 1520. Introduced in 1965, it carried the Air-King-Date 5700/5701 through later production. Contemporary chronometer-rated Oyster Perpetual Date references used a related 1500-series caliber instead.

Auction catalogues often label the date-equipped Cal. 1525 as Cal. 1520. Antiquorum does so on a 1972 ref. 5700, while describing the expected flat hairspring and index-regulated architecture. The chronometer-grade 1560 and 1570 use a Breguet overcoil and Microstella. The Cal. 1525 uses the index regulation associated with the uncertified 5700.

Jewel counts of 17, 25 and 26 reflect parallel market executions. Rolex balance-assembly numbers confirm a flat hairspring for the 1520 and 1525, against a Breguet spring on the 1530 and Microstella on the 1560. The 1525 remains index-regulated. Waddington’s identifies Cal. 1520, 26 jewels, in a circa-1965 Eaton’s ¼ Century Club watch catalogued as ref. 1011, case 1,301,143. See ref. 1011.

Cal. 1560

Cal. 1560, EmmyWatch

detail	value
type	Automatic
jewels	26 (25 in some lot descriptions)
frequency	18,000 vph (2.5 Hz)
power reserve	42h (secondary sources only)
escapement	Straight-line lever
balance	Free-sprung monometallic, Microstella screws
shock	KIF (pattern not named in lots)

Cal. 1560 is commonly dated to 1959 as the chronometer-grade 15xx movement, with a free-sprung balance adjusted to temperature and five positions. Auction catalogues give both 25 and 26 jewels without establishing a pattern. Antiquorum usually describes a Breguet overcoil; its flat-hairspring description for one ref. 1502/1503 is an outlier.

Heritage catalogues Cal. 1560 in a ref. 1013 dated circa 1957, earlier than the commonly cited 1959 date. Both the date and caliber are Heritage’s lot attribution, so this example does not establish when Cal. 1560 entered production. Antiquorum also lists Cal. 1560 in a circa-1962 1013. These records do not date the later change to Cal. 1570. See ref. 1013.

Antiquorum (2006 lot 323, 2024 lot 24), Bonhams and Heritage also catalogue Cal. 1560 in individual ref. 1014 examples. Bonhams dates its masked case 769*** to circa 1951; Bellmans later records serial 769199 as 1962. These are catalogue attributions, and the masked Bonhams number does not confirm that it is the same watch. See ref. 1014.

The Oyster Perpetual ref. 1022 is documented with Cal. 1560 by Bonhams, Pandolfini, Adams, HODINKEE, and 1stDibs; Tajan describes an automatic movement but names no caliber. Bonhams and Adams report 25 jewels; 1stDibs lists 26. Watch-Wiki’s caliber index and Time Connection’s case-parts table also list Cal. 1570 for the 1022. The lists name Cal. 1570, while the five inspected 1022 sale/dealer examples identify Cal. 1560.

Gardiner Houlgate catalogues Cal. 1560 in one ref. 1023, serial 1136xxx, dated circa 1964. Time Connection II’s replacement-parts table lists both Cal. 1560 and 1570 under the reference, without dates or a sequence. The auction record documents one Cal. 1560 example; it does not establish when either caliber entered production.

Matthew Bain lists Cal. 1560 in its circa-1963 ref. 1026. Time Connection II lists 1560/1570 for 1026 in a replacement-parts table, while Bachmann & Scher gives no caliber. The 1560 identification is one dealer attribution; the parts table is compatibility data, not a documented Cal. 1570 installation or changeover. See ref. 1026. Matthew Bain Inc., item 28122; Time Connection II, 1026 row.

Auction catalogues also identify Cal. 1560 in ref. 1024 examples dated circa 1965/66 and circa 1970. Antiquorum lists Cal. 1560 in a ref. 1011 dated 1960, case 546423, and in two lots jointly catalogued as refs. 1010/1011, dated 1960 and 1962. Heritage also lists Cal. 1560 in an undated ref. 1011 sold in 2012. Heritage and Bonhams list Cal. 1560 in individual ref. 1010 lots dated circa 1962 and circa 1967; Antiquorum lists Cal. 1570 in an individual ref. 1010 circa 1968. The Field Manual lists Cal. 1560 for ref. 1010. A 1stDibs item text also names Cal. 1560 for its claimed 1010, though the page title says 1011; treat it as seller-level evidence. These records document both attributions for ref. 1010, and its changeover year remains open; see ref. 1010. Antiquorum catalogues Cal. 1560 in ref. 1501 examples dated 1962 (case 761,220) and 1963 (case 953,774); see ref. 1501, the 1962 lot, and the 1963 lot.

The Vintage Rolex Field Manual assigns Cal. 1560 to proposed monopusher refs. 1074 and 1223, but cites no identified watch or movement evidence for either link. Rolex’s standard Cal. 1560 parts sheet describes a self-winding, sweep-seconds movement and does not document chronograph works. Christie’s catalogues two 1074 wristwatches without naming a caliber. A separate Christie’s 1920s monopusher listing gives 1223 as the case number, not as a verified reference; a ref. 28D1 pocket chronograph uses 1223 as its movement number. Treat both Field Manual caliber assignments as unverified. The Vintage Rolex Field Manual, printed p. 74 Christie’s, model 1074 Christie’s, ref. 1074 case 25433

Cal. 1560 uses free-sprung Microstella regulation; Cal. 1530 uses an index. Watches made from 1959 to 1965 were tested by the Bureaux Officiels de Contrôle de la Marche des Montres, usually under collective certificates and to a standard around −1/+10 seconds per day in five positions. COSC did not exist until September 1973, so describing an early 1560 as COSC-certified is anachronistic.

Factory balance 7980 is used in the 18,000-vph chronometer group: 1555, 1556, 1560 and 1565. Later replacement part 8106 and balance bridge 8102 span both 18,000- and 19,800-vph family members, so a serviced 1560 may carry the later balance. Documented fitments include the four-line 5512, 5504 and Explorer 1016. The GMT-Master 1675 instead used the 1565 to about the 1.4-million serial range and the 1575 thereafter. Family-wide bridge engravings explain 1675 movements marked 1560 or 1570; a base 1560 lacks both calendar and 24-hour works. Although 1570 became the new fitment in 1965, 1560 movements appear in Explorers until about 1967.

Cal. 1565

Cal. 1565, EmmyWatch

detail	value
type	Automatic
jewels	25–26 (sources disagree)
frequency	18,000 vph (2.5 Hz)
power reserve	42h (registry; 44h in some secondary tables)
escapement	Straight-line lever
balance	Free-sprung, Microstella
shock	KIF

Produced from 1959 to 1965, Cal. 1565 is the early ref. 1675's "caller" GMT movement: its 24-hour hand remains linked to the main hour hand rather than independently adjustable. Rolex kept that layout until Cal. 3085. The 1565 introduced a free-sprung Breguet overcoil with Microstella regulation to this lineage, replacing the index used by earlier sport calibers. Rolex's Cal. 1565 parts sheet describes an automatic calendar movement, shows "1560" engraved on its self-winding bridge, and lists part 7956, the date-indicator seating, for refs. 1500, 1501 and 1503. The Cal. 1575 parts catalogue lists date-indicator parts for those same case references. The Vintage Rolex Field Manual also lists ref. 1500 in its Cal. 1565 Date table (The Vintage Rolex Field Manual, caliber table). These factory lists document service-parts applications; movement-level inspection determines the caliber fitted to a particular watch. Auction catalogues call ref. 1501 Cal. 1560 or 1570, matching the bridge numbers shown in the 1565 and 1575 parts sheets. The records leave watch-specific fitment and changeover years unresolved. See ref. 1500, ref. 1501 and ref. 1503.

Cal. 1570

Cal. 1570, open caseback

detail	value
type	Automatic
jewels	26
frequency	19,800 vph (2.8 Hz)
power reserve	48h
size	12.5′′′ (28.2mm)
escapement	Straight-line lever
balance	Free-sprung monometallic, four Microstella screws
shock	KIF (Flector or Elastor)

Cal. 1570 is the 19,800-vph revision of the 1560, introduced in 1965. Christie’s identifies Cal. 1570 in ref. 1011 case 692498, dated circa 1962; its lot chronology overlaps the ref. 1011 Cal. 1560 examples and does not establish a changeover. See ref. 1011. Monaco Legend lists Cal. 1570 in a 1966 pink-gold 1013, Gazette Drouot in a circa-1968 example and Rago in a 1978 example. The 1013 records document both calibers but leave their changeover unresolved. See ref. 1013. One Artcurial ref. 1005 lot is catalogued with Cal. 1550, despite a chronometer-dial description; other 1005 catalogues list 1560 or 1570. This single lot does not establish a 1005 movement variant or resolve whether the movement is original. It retains the free-sprung Breguet overcoil and Microstella regulation, with adjustment to temperature and five positions. Family-wide bridge engraving causes date movements such as the 1575 in a ref. 1665 to appear marked 1570; the engraving alone does not identify the exact caliber. Phillips identifies Cal. 1570 in a circa-1985 ref. 1024, while Dorotheum lists it on a circa-1965/70 example; those ref. 1024 dates overlap its Cal. 1560 records. Christie’s, Antiquorum, Phillips, Dorotheum and Bonhams also catalogue Cal. 1570 in ref. 1501 examples; see ref. 1501. These lot labels do not establish a 1501 changeover year.

Waddington’s lists Cal. 1570 in ref. 1023/8B and dates it circa 1964. That estimate predates the 1965 start date used here for Cal. 1570; Pergola’s unofficial chart places serial 902827 in 1962. Hess and Watch.de identify Cal. 1570 on other 1023 listings, and a 2022 Rolex Forums photograph shows a rotor marked 1570 inside an outer case stamped 1023. Kaplans also lists Cal. 1570 for serial 2,186,841; Watch.de masks its serial as 2186xxx, and their other matching details suggest a repeat listing. These records document the caliber on individual watches, but they do not establish first fitment or a changeover; see 1023.

The balance has four Microstella screws in two opposing pairs, not two. Rolex required equal adjustment within each pair to preserve poise. The larger pair changes rate by about two seconds per day and the smaller by about one. On this family the screws sit in the balance rim; the later 3135 platform moves its Microstella nuts to the inner rim.

KIF's circa-1972 material catalogue lists Flector and Elastor settings for Rolex; it does not list Ultraflex. Auction catalogues name only a shock absorber, while Rolex part 8065 serves the upper balance setting across the 1520, 1530, 1560 and 1570. The available records support Flector and Elastor.

Hacking appeared gradually around 1971–72, with timing varying by model. Cal. 3035 began replacing the 1570 in new production from 1977, but the Explorer 1016 retained it until 1988–89. The documented diameter is 12.5 lignes, or 28.2mm; the often-published 28.5mm is a rounded conversion. Published heights conflict.

Cal. 1575

Cal. 1575, EmmyWatch

detail	value
type	Automatic
jewels	26 (25 per Ashton Tracy)
frequency	19,800 vph (2.8 Hz)
power reserve	48h
escapement	Straight-line lever
balance	Free-sprung monometallic, Microstella screws (1570 balance)
shock	KIF (Flector or Elastor)

Cal. 1575 adds calendar work to the 1570; the GMT execution also adds a 24-hour train. Antiquorum and Sotheby's give 26 jewels, while watchmaker Ashton Tracy's 2018 Quill & Pad study gives 25. Tracy records a 48-hour power reserve; the often-published 50-hour figure lacks support.

Rolex engraved the 1575 bridge "1570," so that marking on a ref. 1680 or 1675 identifies the caliber family. Factory parts records distinguish 1565G, 1575, 1575G and 1575GMT. Date and GMT versions are separately catalogued builds, and the GMT parts also circulated as a conversion set for a standard 1560 or 1570.

The 1575 shares factory balance assembly 8106 with the 1570 and related family members. It has shock protection on the escape wheel on both dial and movement sides, as well as on the balance. The Vintage Rolex Field Manual lists ref. 1500 as a Date fitment in its Cal. 1575 table (The Vintage Rolex Field Manual, caliber table); a Rolex Cal. 1575 parts catalogue lists date-indicator parts for refs. 1500, 1501 and 1503. Auction catalogues more often describe 1500 examples as Cal. 1570. Bob’s Watches explains the 1570 bridge engraving on date-equipped 1575-family movements; the engraving alone does not establish the caliber beneath it. The available records do not identify a watch-specific changeover. Other documented fitments include the Submariner 1680, GMT-Master 1675 from about the 1.4-million serial range, Explorer II 1655 and Sea-Dweller 1665.

GMT-Master line

Early GMT-Master movements synchronized the hour hands. Published references and auction catalogues name calibres 1030, 1036, 1065 and 1066 for the 6542; the sources do not give a consistent changeover chronology. Cal. 1565, 1575 and 3075 retained the synchronized, or "caller," layout through the 1675 and 16750 generations. Cal. 3085 introduced an independently adjustable local-hour hand. Cal. 3175 kept the synchronized layout in the 16700 until 1999, alongside calibres 3185 and 3186 in the 16710.

Cal. 1036

Cal. 1036, EmmyWatch

detail	value
type	Automatic
jewels	25
frequency	18,000 vph (2.5 Hz)
power reserve	42h (secondary sources only)
escapement	Straight-line lever (inferred, 1030 base)
balance	Monometallic (inferred, 1030 base)
shock	KIF (inferred)

The Field Manual lists Cal. 1036 for the 6542, and Monochrome describes it as a Cal. 1030 with a 24-hour train. Sotheby's catalogues identify several individual 6542s with Cal. 1030, while other lots name 1065 or 1066. These attributions leave the 1036's place in the reference's production run unresolved. Period chronometer certificates came from the Bureaux Officiels; COSC began in 1973.

Published chronologies differ: a Phillips catalogue essay dates the 6542 release to 1954, while Rolex places the GMT-Master in 1955. The relationship between those dates remains unresolved in the cited sources.

The listed escapement, balance and shock protection are inferred from the Cal. 1030 base; no Cal. 1036 source documents them directly. Auction catalogues seldom identify a 6542 movement as Cal. 1036, so those three specifications remain provisional.

Cal. 1065

Cal. 1065, EmmyWatch

detail	value
type	Automatic
jewels	25
frequency	18,000 vph (2.5 Hz)
power reserve	42h (secondary sources only)
escapement	Straight-line lever (inferred, 1030 base)
balance	Monometallic (inferred, 1030 base)
shock	KIF (inferred)

Auction catalogues identify Cal. 1065 in individual 6542 and 6609 examples as an automatic movement with 25 jewels. The Field Manual also lists it for the 6542. For ref. 6609, Sotheby's, Monaco Legend and Phillips identify Cal. 1065; Christie's and Antiquorum name Cal. 1066, and Phillips lot 118 lists Cal. 1030. These are lot-level attributions; they do not settle the 6609 changeover or Cal. 1065's production dates and position relative to calibres 1030, 1036 and 1066. Published 42-hour reserve figures come from secondary sources.

The escapement, balance, and shock rows likewise derive from the Cal. 1030 base. Cal. 1066 cataloguing supports that family relationship, but these details have not been documented directly on a Cal. 1065.

Cal. 1066

Cal. 1066, stamped "1066," butterfly rotor engraved "Rolex Perpetual Patented," EmmyWatch

detail	value
type	Automatic
jewels	25
frequency	18,000 vph (2.5 Hz)
power reserve	42h

Auction catalogues identify Cal. 1066 in steel and gold 6542 examples, including watches dated circa 1958 and 1959. Christie's and Antiquorum also catalogue individual 6609 examples with Cal. 1066. The Field Manual lists the caliber for the 6542 as well. Its published specification is 18,000 vph and 25 jewels; Antiquorum describes a straight-line lever escapement, monometallic balance adjusted to temperature and five positions, shock absorber, and self-compensating Breguet hairspring. The available records place Cal. 1066 in late examples, but do not establish it as the final fitment or date a change from Cal. 1065.

The regulator and balance specification remain uncertain. Cal. 1030 descriptions name an index regulator, while Cal. 1066 descriptions omit it; one 6542 is catalogued with a free-sprung Glucydur balance. This may mark a running change or inconsistent cataloguing. A circa-1959 Phillips example directly confirms the Cal. 1066's butterfly rotor.

Published examples dated circa 1958 and 1959 carry different movement labels. A steel watch has a IV.1958 caseback; auction catalogues date two gold watches to 1959. These individual records show more than one caliber in late examples.

Cal. 3075

Cal. 3075, engraved "3075," EmmyWatch

detail	value
type	Automatic
jewels	27
frequency	28,800 vph (4 Hz)
power reserve	48h
escapement	Straight-line lever
balance	Free-sprung monometallic, Microstella screws
balance support	Balance cock (3035 generation)
shock	KIF (inferred; lots record only "shock absorber")

Cal. 3075 carried the synchronized "caller" GMT layout into the 16750 generation. It has 27 jewels, a straight-line lever escapement, a monometallic balance adjusted to temperature and five positions, a free-sprung Breguet hairspring regulated by Microstella screws, hacking, and quickset. The quickset advances only the date wheel.

The balance is monometallic, not Glucydur. Catalogue descriptions identify Microstella screws but do not record their count, material, or position on the rim. They also name a shock absorber without identifying its maker, so the KIF attribution remains inferred from Rolex practice of the period.

The 3075 belongs to the 3035 generation and uses its cantilevered balance cock. Cal. 3175 and 3185 later introduced a balance bridge anchored at both ends. Its start date is disputed: the 16750 did not appear in a Rolex catalogue until 1981, while Antiquorum dates production of the 16758 to 1979. Known fitments are the steel 16750, steel-and-gold 16753, and gold 16758. The 3075 also moved the GMT hand above the hour hand, reversing the Cal. 1575 stack; later GMT calibers retained that arrangement.

Cal. 3085

Cal. 3085, EmmyWatch

detail	value
type	Automatic
jewels	27
frequency	28,800 vph (4 Hz)
power reserve	48h
size	28.5mm × 6.3–7.2mm (sources disagree)
escapement	Swiss lever
balance	Free-sprung, Microstella
shock	KIF (per published specs, unconfirmed)

Cal. 3085 ran from 1983 to 1989 on the Cal. 3035 platform, with 27 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, and chronometer certification. It was the first Rolex caliber to separate the local-hour hand from the 24-hour hand. The crown jumps the local hour forward or backward in one-hour steps without disturbing the minutes, seconds, or home-time hand. The date advances only by cycling the local-hour hand, so the movement has no direct quickset date.

Published thickness figures conflict. Grail Watch Reference gives 6.3mm, while Caliber Corner gives 7.2mm against the Cal. 3185's 6.45mm. The 16760's thick movement and case produced the "Fat Lady" and "Sophia Loren" nicknames. Cal. 3085 appeared only in the 16760 GMT-Master II and 16550 Explorer II. Published specifications agree on a Breguet hairspring and Microstella regulation, but KIF shock protection has not been confirmed by an auction description or Rolex document.

Cal. 3175

Cal. 3175, EmmyWatch

detail	value
type	Automatic
jewels	31
frequency	28,800 vph (4 Hz)
power reserve	48h
escapement	Swiss lever
balance	Free-sprung Glucydur, Microstella
balance support	Balance bridge (3135 generation)
shock	KIF Elastor (3100-family text, not lot-confirmed)

Cal. 3175 ran from 1988 to 1999 with 31 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, quickset, and chronometer certification. Auction descriptions confirm the jewel count and adjustment to temperature and five positions. Published 3100-family specifications support a free-sprung Glucydur balance, Microstella regulation, Breguet hairspring and KIF Elastor setting. No examined Cal. 3175 lot confirms KIF Elastor.

Architecturally, Cal. 3175 is a Cal. 3135 with a fixed 24-hour hand. It uses the 3135's balance bridge, anchored at both ends, where Cal. 3075 used a cantilevered cock. The 24-hour hand remains linked to the local hour hand, so a second time zone is read from the rotating bezel. The 16700 kept this synchronized layout while the rest of the line moved to the jumping-hour Cal. 3185.

Cal. 3175 appeared only in the 16700 and was Rolex's last fixed GMT movement. Reports of factory Cal. 3185 fitment in late 16700s rest on a contradictory parts listing and a rebuilt watch; documented Cal. 3185 fitment belongs to the 16710. Sotheby's has incorrectly described Cal. 3175 as having an independent GMT hand. The accepted 16700 production span is 1988–1999, although Fratello gives 2001 in one account. The 1997 change from tritium to Super-LumiNova affected the dial, not the movement.

Cal. 3185

Cal. 3185, engraved "3185"

detail	value
type	Automatic
jewels	31
frequency	28,800 vph (4 Hz)
power reserve	48h
size	6.45mm
balance	Free-sprung Glucydur, four Microstella nuts

Cal. 3185 ran from 1989 to about 2007. Derived from Cal. 3135 with added 24-hour work, it has 31 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, an independently adjustable local-hour hand, chronometer certification, and KIF Elastor shock protection. It powered the 16710, 16713, 16718, and 16570, replacing Cal. 3085 in the GMT-Master II and Explorer II.

The balance carries four Microstella nuts arranged as two opposing pairs of different sizes. Rolex's Microstella wrench instructions require equal adjustment of both nuts in a pair to preserve the balance-wheel poise. Adjusting one without its opposite puts the wheel out of poise.

Published Cal. 3085 thickness figures span 6.3 to 7.2mm. Cal. 3185 is 6.45mm, so it is thinner than the thicker 16760 specification but not every published 3085 measurement. That helped the 16710 sit flatter than the "Fat Lady" 16760. During setting, the 24-hour hand may twitch as the local hour jumps; this is a screening clue, not proof of caliber identity.

The date is corrected by moving the local-hour hand through midnight; there is no separate direct quickset for the date disc.

Cal. 3186

Cal. 3186, engraved "3186"

detail	value
type	Automatic
jewels	31
frequency	28,800 vph (4 Hz)
power reserve	50h
size	28.5mm × 6.45mm
escapement	Swiss lever
balance	Monometallic, free-sprung
regulator	Microstella screws, no index
shock	Shock-absorber, pre-Paraflex

Cal. 3186 predates the steel GMT-Master II transition of 2007; the gold example discussed below was sold in 2006. It added a Parachrom hairspring to the Cal. 3185 base while retaining 31 jewels, a 28,800 vph frequency, hacking, an independently adjustable local-hour hand, and chronometer certification; reserve increased to 50 hours. It powered late 16710 production and the ceramic-bezel 116710LN, 116710BLNR, and 116719BLRO.

The movement has a straight-line lever escapement, monometallic balance adjusted to temperature and five positions, shock protection, a free-sprung Breguet-form hairspring, Microstella regulation, and hacking. One Antiquorum description calls the hairspring blued steel, but Cal. 3186 uses Parachrom, a niobium-zirconium alloy coloured by an oxide layer rather than tempering.

Cal. 3186 retains the Cal. 3135 architecture used by the 3185: 28.5mm diameter, 6.45mm height, 28,800 vph, and 31 jewels. It also keeps the plain-bearing oscillating-weight axle, part 568, shared with Cal. 3130, 3135, 3155, and 3175. Axle condition must be assessed during service.

Rolex introduced Cal. 3186 as a running change, leaving its start date unsettled. Steel 16710 examples begin among late Z- and M-series cases; the lowest documented example is Z 5786xx, but higher Z-series watches can still contain Cal. 3185. Gold references changed earlier. A D-series 116718 catalogued with Cal. 3186 was sold in August 2006, placing the movement in production before the commonly cited 2007 steel transition.

Auction catalogues conflict on the 116758 SARU. Christie's assigns Cal. 3185 to examples dated circa 2006 and 2007 (lot 6042618; lot 6248960); Sotheby's assigns Cal. 3186 to a circa-2007 watch (lot 45). Phillips (lot 14) and a later Christie's lot (lot 6167024) also list 3186. Rolex's 2008 US catalogue specifies a 31-jewel chronometer without a calibre number. These records leave the reference's movement transition undated.

Both Cal. 3185 and 3186 index the local-hour hand with a jumping-hour click. Cal. 3186 reworked the parts and reduced slack between the drive-train wheels. On Cal. 3185, the 24-hour hand twitches when the local hour jumps; on Cal. 3186, it remains still. Treat this as a screening clue and confirm the caliber by inspecting the movement.

Failure of the local-hour hand to index in one-hour steps calls for examination of the setting mechanism. The symptom alone does not identify which part needs replacement.

The date is corrected by moving the local-hour hand through midnight; there is no separate direct quickset for the date disc.

Cal. 3187

Cal. 3187, official Rolex photo, engraved "3187," blue Parachrom hairspring, free-sprung Microstella balance

detail	value
type	Automatic
jewels	31
frequency	28,800 vph (4 Hz)
power reserve	48–50h (sources disagree)
size	30.97mm (contested; 28.5mm also published)
escapement	Swiss lever
balance	Monometallic, free-sprung
regulator	Microstella screws, no index
shock	Paraflex

Cal. 3187 is an enlarged Cal. 3186, widened to move the date window outward in the 42mm Explorer II case. It powered only the 216570 from 2011 to 2021, before Cal. 3285 replaced it in the 226570. The Parachrom hairspring, Breguet overcoil, and independently adjustable local-hour hand carry over from the GMT lineage. Paraflex is new here, replacing the KIF Elastor used by Cal. 3185. Within the GMT and Explorer II lineage covered on this page, Cal. 3187 is the first entry listed with Paraflex.

Cal. 3187 uses a larger baseplate and reworked surrounding parts but retains the Cal. 3186 regulating organ: a straight-line lever escapement, free-sprung monometallic balance under a full bridge, and Microstella regulation without an index. Auction catalogues confirm 31 jewels but do not itemize those inherited components.

Rolex launched the 216570 and Cal. 3187 together in March 2011 for the Explorer II's fortieth anniversary. The 42mm case required the larger movement, while the orange 24-hour hand recalled the 1655. Both remained in production until 2021, and no other reference used the caliber.

Two documented unit commissions use Cal. 3187. A 2012 white-dial 216570 made for members of the British Special Air Service carries "Who Dares Wins," the winged-dagger badge, and its owner's identifiers. A circa-2015 example numbered 40/48 was made for the UK Attack Helicopter Force. These were unit commissions rather than ministry-issued watches and should not be classified with the 5513 MilSub.

The local-hour hand should index in one-hour steps during setting. Irregular movement requires inspection of the mechanism.

The −2/+2 rating applies only after Rolex redefined Superlative Chronometer in 2015. Earlier watches carried the COSC −4/+6 seconds-per-day standard for the uncased movement; later examples were tested again by Rolex as complete watches. The underlying caliber did not change beyond regulation.

Modern sport calibers (1988–2023 coverage)

Cal. 3000 introduced a 28,800-vph no-date movement, followed by Cals. 3130 and 3132. Cal. 3135 powered three decades of Submariner Date production.

Cal. 3000

Cal. 3000

detail	value
type	Automatic
jewels	27
frequency	28,800 vph (4 Hz)
power reserve	42h (48h in some sources)
size	28.5mm × 5.8mm
balance	Adjustable-mass, flat hairspring

Cal. 3000 is the no-date member of the 3000 family, used from about 1990 to 2001 in the Air-King 14000 and 14010, Submariner 14060, and Explorer 14270. The often-quoted 1988 start belongs to Cal. 3135. The Air-King changed to reference 14000M in 2000, while the Explorer became the 114270 and the Submariner adopted Cal. 3130 in 2001. Published power-reserve figures conflict at 42 and 48 hours; no Rolex figure settles the difference.

Cal. 3000 uses a flat hairspring, a useful distinction from the Breguet overcoil in Cal. 3130. Microstella adjustment sets the rate without an index, the hairspring is glued to the balance stud, and shock protection is KIF. COSC certification used the standard −4/+6 seconds-per-day tolerance.

Cal. 3035

Cal. 3035, engraved "3035," EmmyWatch

detail	value
type	Automatic
jewels	27
frequency	28,800 vph (4 Hz)
power reserve	48h
balance	Free-sprung, four Microstella screws
shock	KIF Elastor

Cal. 3035 ran from 1977 to 1988 in the 16800, 168000, 16808, and 16803. It was the first quickset Submariner caliber, with 27 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, and chronometer certification. Compared with the Cal. 1570 generation, it increased frequency from 19,800 vph and added a crown position that advances the date wheel directly. Its free-sprung Nivarox Breguet overcoil is regulated by four Microstella screws and protected by KIF Elastor.

Exact-reference auction catalogues also identify Cal. 3035 in Datejust ref. 16003 examples. The 1977–1988 dates above apply to the listed Submariner references, not to the caliber’s full use across Rolex models. Dorotheum, case 5,880,264; Kaplans, serial 5,230,455; Morton, lot 134.

Two construction details separate it from Cal. 3135. Its balance sits on a cantilevered cock, and its hairspring is glued to the stud. Cal. 3135 uses a bridge anchored at both ends and a laser-welded hairspring stud.

Cal. 3130

Cal. 3130, engraved "3130," EmmyWatch

detail	value
type	Automatic
jewels	31
frequency	28,800 vph (4 Hz)
power reserve	48h
size	28.5mm × 5.85mm
escapement	Swiss lever
balance	Monometallic Glucydur, free-sprung
regulator	Microstella screws, no index
shock	KIF Elastor

Cal. 3130 is the time-only successor to Cal. 3000, used in the 14060M, 114060, 114270, and 114200. It brought a full balance bridge, a larger balance wheel, and a Breguet overcoil hairspring. Rolex's parts sheet identifies Cal. 3135 as the base and gives 28.5mm diameter, 5.85mm height, 28,800 vph, and 31 jewels. Published introduction dates range from 1999 to 2001; the precise year remains unsettled.

Cal. 3000 supports its balance from a cock anchored on one side; the 3130 uses a bridge secured at both ends, which stabilizes endshake under lateral shock. Its Glucydur balance is free-sprung, with Microstella nuts setting the rate without an index. KIF Elastor shock protection distinguishes it from the Paraflex-equipped Cal. 3132. At 5.85mm it is 0.15mm thinner than Cal. 3135 because it omits the date mechanism. The main plate is the dedicated part 3130-100, although some smaller components retain 3135 part numbers.

The 14060M initially used Cal. 3130 without COSC certification and carried a two-line dial. Certification arrived in late 2007, adding the two-line "Superlative Chronometer Officially Certified" inscription. The movement itself did not change.

The oscillating-weight axle uses a plain bearing. A service assessment should check the rotor and its bearing for wear and contact with surrounding parts.

Cal. 3131, announced in 2007, adapts the 3130 for magnetic resistance with a blue Parachrom hairspring, a paramagnetic nickel-phosphorus escapement, and a two-part soft-iron shield around the movement. It powered the Milgauss 116400 and 116400GV, then the Air-King 116900.

Cal. 3132

Cal. 3132

detail	value
type	Automatic
jewels	31
frequency	28,800 vph (4 Hz)
power reserve	48h
size	30.97mm (contested; 28.5mm also published)
escapement	Swiss lever
balance	Monometallic Glucydur, free-sprung
regulator	Microstella screws, no index
shock	Paraflex

Cal. 3132 powered the 39mm Explorer 214270 from 2010 until the 36mm successor arrived in 2021. It is a Cal. 3130 with a Parachrom hairspring and Paraflex shock protection, retaining 31 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, and chronometer certification.

The base architecture remains a straight-line lever escapement with a free-sprung Glucydur balance under a full bridge, Microstella regulation, and no index. Paraflex replaced the 3130's KIF Elastor settings; Rolex's published material claims up to 50 per cent greater shock resistance than KIF. That comparison is a manufacturer claim, not an independent test. The blue Parachrom hairspring replaced Nivarox with a paramagnetic niobium-zirconium alloy whose colour comes from a patented oxide treatment.

Cal. 3132 brought Parachrom and Paraflex to the time-only professional line. Parachrom had appeared in Cal. 4130 in 2000, but the Submariner did not receive both features until Cal. 3230 in 2020.

Both dial generations of the 214270 use Cal. 3132. The 2016 revision lengthened the hands and added luminous filling to the 3, 6, and 9 numerals, without changing the movement. Cal. 3132 also retains the 3130’s plain-bearing oscillating-weight axle.

Rolex’s product sheet lists Cal. 3132 for the Oyster Perpetual 39 ref. 114300. Phillips catalogues a white-dial 114300, case P470X511, as Cal. 3230 in its 2023 Geneva lot 21 and 2025 Hong Kong lot 8048; the matching case number and June 2020 guarantee suggest the records concern one watch. It also catalogues a circa-2015 blue-dial 114300, case 908YN729, as Cal. 3230 in 2025 Hong Kong lot 924. The catalogue descriptions conflict with Rolex’s 114300 product sheet and do not establish factory fitment; replacement or catalogue error remains unresolved. See Reference:114300.

Rolex redefined Superlative Chronometer in 2015, changing the guaranteed rate from COSC's −4/+6 seconds per day on the uncased movement to −2/+2 on the cased watch after additional in-house testing. The movement did not change, so early and late 214270 examples carry different rate guarantees.

Cal. 3135

Cal. 3135, official Rolex photo, engraved "3135," 31 jewels

detail	value
type	Automatic
jewels	31
frequency	28,800 vph (4 Hz)
power reserve	48h
size	28.5mm
escapement	Swiss lever
balance	Free-sprung Glucydur, four Microstella nuts
regulator	Free-sprung, no index
shock	KIF (never Paraflex)

Cal. 3135 ran from 1988 to 2021 with 31 jewels, a 28,800 vph frequency, 48 hours of reserve, hacking, quickset, and chronometer certification. It powered the 16610, 16613, and 16618 through the 116610 generation. The Submariner changed to Cal. 3235 with the 126610 on 1 September 2020, but the Oyster Perpetual Date 34 references 115200 and 115234 kept Cal. 3135 in production into 2021. Later end dates conflate it with Cal. 3131. The movement has rhodium plating, bevelled and polished screws, and a two-piece axle-style bidirectional rotor.

The conventional Swiss lever escapement is paired with a free-sprung Glucydur balance. With no index or curb pins, four Microstella nuts on the inside of the rim set the rate by changing the wheel's inertia. Older 1530-family balances place their adjustment screws on the outside. Cal. 3135 uses a Breguet overcoil and laser-welds the hairspring to its stud, replacing the glued joint used by Cal. 3035.

The main architectural change from Cal. 3035 is the balance bridge. Part 3135-120 is secured at both ends and carries height-adjusting nuts, keeping the pivots aligned under load and allowing endshake adjustment without shims. It also prevents the hairspring from fouling a cantilevered balance cock, a known Cal. 3035 problem. Cal. 3135 increased the jewel count from 27 to 31 and uses a larger balance wheel.

Cal. 3135 used KIF shock protection throughout its run and never received Paraflex. Rolex assigned new caliber numbers to Paraflex versions: 3130 became 3132, 3155 became 3156, and 3186 became 3187. The larger Paraflex date movement for the Datejust II was Cal. 3136. A 16610 or 116610 described as having Paraflex is misidentified.

Parachrom arrived during the Cal. 3135 run, but the transition date is unsettled. The niobium-zirconium alloy receives a uniform anodised oxide layer about 50 nanometres thick, which gives the hairspring its blue colour and stabilizes its restoring torque. Published dates for its adoption in Cal. 3135 range from about 2005 to 2009, with transitional examples reported on both sides. The ceramic-bezel 116610 uses it consistently from 2010. The spring's colour provides only a rough dating marker.

The reversing wheels transmit winding power when the rotor turns in either direction. Rolex dates their patent to 1952 and the introduction of their red surface treatment to 1957. Their colour identifies the component type, not Cal. 3135 by itself.

Earlier movements carried COSC's −4/+6 seconds-per-day standard. From 2015, Rolex applied its −2/+2 Superlative Chronometer test to the complete watch without changing the caliber. Derivatives include Cal. 3155, 3175, 3185, 3186, 3187, and the no-date 3130, 3131, and 3132.

Milgauss

Auction catalogues assign Cal. 1080 to early Milgauss examples, though a later catalogue labels the same 6541 movement number Cal. 1055. Cal. 1580 derives from the 1530 platform; Cal. 3131 derives from Cal. 3130.

Cal. 1080

detail	value
type	Automatic
jewels	25 listed for Christie’s case 145'111 and Sotheby’s case 412'479
documented fitment	Milgauss 6543 and 6541 examples; one 6541 movement number carries conflicting 1080 / 1055 catalogue labels
base relationship	Revolution describes it as modified from Cal. 1030

Christie’s lists Cal. 1080 in 6543 case 145'111. Revolution and Watch-Wiki also assign the caliber to the 6543; Revolution describes a Cal. 1030 relationship. Watch-Wiki is a secondary reference index, and it does not resolve Christie’s Cal. 1065 label for case 145'159. Sotheby’s called movement N726507 in 6541 case 412'479 Cal. 1080 in 2018; Phillips listed the same case and movement number as Cal. 1055 in 2026. The surviving records do not establish a caliber sequence.

Cal. 1580

Cal. 1580, marked "26 Jewels, Adjusted Six 6 Positions" — EmmyWatch

detail	value
type	Automatic
jewels	26
frequency	19,800 vph (2.8 Hz)
power reserve	48h
size	28.5mm × 5.75mm
escapement	Straight-line lever
balance	Free-sprung monometallic, Microstella screws
regulator	None — free-sprung
shock	Shock absorber

Cal. 1580 is associated exclusively with the Milgauss 1019 during its 1960–1988 run, subject to the early-production dating conflict below. It shares the 1530-derived platform with Cal. 1570 and 1575, and gained hacking around 1972. A soft-iron inner shield around the movement provides the magnetic protection, making the 1019 thicker than contemporary Submariner and GMT-Master cases using the same movement family. Parts interchange broadly across the 1520/1525/1530/1535/1555/1556/1560/1565/1570/1575/1580 group.

Cal. 1580 has 26 jewels, a straight-line lever escapement, a monometallic balance adjusted to temperature and five positions, shock protection, and a Breguet hairspring. Antiquorum describes the hairspring as free-sprung white metal with Microstella regulation. That matches Cal. 1560 and 1570 on the same platform, although no second auction house specifies the regulation system.

The case provides the magnetic shielding. A gilt-metal anti-magnetic cap and the surrounding inner case absorb the field. Cal. 1580 uses the standard 1530-family balance and hairspring inside the shielded case. Rolex added hacking in 1972 with the corresponding sport-caliber revision.

Watch Doctor’s chart assigns Cal. 1580 to 1963, later than the usual dating of the first 1019s to around 1960. That discrepancy does not establish that early 1019s contained a different caliber. A proposed alternative needs a documented watch or a Rolex record.

Cal. 3131

Cal. 3131 from a Milgauss 116400GV, auto bridge and gold reversing wheels

detail	value
type	Automatic
jewels	31
frequency	28,800 vph (4 Hz)
power reserve	48h
size	28.5mm
escapement	Nickel-phosphorus escape wheel & pallet fork
balance	Free-sprung monometallic, Microstella
shock	KIF

Cal. 3131 is a no-date Cal. 3130 derivative announced at Baselworld 2007 for the Milgauss 116400 and 116400GV "Glace Verte." From 2016 it also powered the Air-King 40 reference 116900. Magnetic protection has three parts. A two-piece ferromagnetic shield encloses the movement, with one half secured on the dial side and the other beneath the outer caseback; the inner back carries a capital "B" and arrow, the symbol for magnetic flux density. The movement also uses a paramagnetic blue Parachrom hairspring and an amorphous nickel-phosphorus escape wheel and pallet fork.

Cal. 3131 remained COSC-certified throughout its run, with KIF shock protection and a conventional Swiss lever escapement. It never received Chronergy or Paraflex. Rolex applied the tighter −2/+2 seconds-per-day Superlative Chronometer standard from 2015, so later 116900 and 116400GV examples carry the revised rating without a corresponding movement change. The Air-King remained in production to 2022 and the Milgauss to 2023.

Daytona chronograph (manual-wind)

The manual-wind Daytona used Valjoux 72 architecture from 1963 through 1988. Across five caliber numbers, Rolex progressively refinished and re-rated the Valjoux 72 ébauche.

Valjoux joined the Ebauches SA group in 1944 and was later folded into ETA, though the Valjoux name remained in use through the end of Cal. 72 production in 1974. At least 62,000 Valjoux 72/23 movements are recorded in Rolex cases across more than 40 references, about 7 per cent of total output. Heuer, Universal Genève and Longines also used the base. Rolex examples differ in their finishing and adjustment.

Cal. 72

Valjoux 72 ébauche, caliber "72" stamped at 6 o'clock beside the Valjoux logo, plate marked "Seventeen 17 Jewels Unadjusted," stock index regulator with F/A–S/R scale — the untouched configuration Rolex fitted as Cal. 72. This example's chronograph bridge is signed Heuer-Leonidas SA

detail	value
type	Manual
complication	Chronograph
jewels	17
frequency	18,000 vph (2.5 Hz)
power reserve	48h
escapement	Swiss lever
shock	Incabloc

Auction catalogues identify Cal. 72 in individual ref. 6034 watches dated circa 1952–1955. One Antiquorum lot instead lists a 13-ligne, 17-jewel movement without a caliber name. These descriptions belong to the named watches; they do not establish one designation across every 6034. Christie's, circa-1953 case 907407 Sotheby's, circa-1952 case 847427 Phillips, circa-1953 case 847307 Antiquorum, 13-ligne example

Cal. 72 was also used in the pre-Daytona ref. 6234 from about 1955 to 1961, where it remained close to the Valjoux ébauche. Rolex retained its index regulator, flat hairspring and Incabloc protection. Auction records document the bare Cal. 72 designation on examples from 1957 and around 1960; published production dates for the 6234 end in either 1960 or about 1961.

Cal. 72A

detail	value
type	Manual
complication	Chronograph
jewels	17
frequency	18,000 vph (2.5 Hz)
power reserve	48h
escapement	Swiss lever
shock	Incabloc

Cal. 72A appears in late ref. 6234s from the late 1950s to about 1961. It retains the index regulator and flat hairspring that Cal. 72B would replace, making it a Rolex-finished but otherwise conventional Valjoux 72 execution. The meaning of the ROW stamp remains uncertain: Sotheby's associates it with US importation, while Grail Watch Reference reads it as Rolex Werke. Neither interpretation is supported by a known Rolex document.

Cal. 72B

Rolex-signed Valjoux 72-family movement, seventeen jewels — caliber sub-variant not distinguishable from the engraving alone

detail	value
type	Manual
complication	Chronograph
jewels	17
frequency	18,000 vph (2.5 Hz)
power reserve	48h
escapement	Swiss lever
balance	Microstella, adjustable inertia
shock	KIF (often Flector)

Used in the ref. 6238 and the last 6234s, Cal. 72B marks Rolex's first substantial reworking of the Valjoux base. The index regulator gave way to a Microstella adjustable-inertia balance, the flat hairspring to a Breguet overcoil, and Incabloc protection to KIF, often in its clover-shaped Flector form. The caliber also has the earlier screwed setting lever, later replaced by a pusher type.

The transition date is disputed. Dody Giussani's text for Ultimate Rolex Daytona dates the complete replacement of Cal. 72A to 1966, while auction records identify Cal. 72B in ref. 6234 examples from around 1961. Giussani finds no substantial mechanical difference between the 72B and 722 and notes that Rolex used both names in its technical documents. The regulating organ changed before Rolex consistently adopted the later caliber name.

Cal. 722

Rolex-signed Valjoux 72-family movement, seventeen jewels — caliber sub-variant not distinguishable from the engraving alone

detail	value
type	Manual
complication	Chronograph
jewels	17
frequency	18,000 vph (2.5 Hz)
power reserve	48h
escapement	Swiss lever
balance	Microstella, adjustable inertia
shock	KIF (often Flector)

Cal. 722 powered the refs. 6239, 6240 and 6241, including examples with "Paul Newman" dials. Its column wheel controls a horizontal clutch through a coupling yoke. Engagement can make the chronograph hand jump slightly forward or back at the start, a trait later removed by the vertical clutch in Cal. 4130.

The position of the "Rolex Genève" inscription on the dial-side plate distinguishes Cal. 722 from the 722-1 that followed. The designations otherwise overlap: Christie's records Cal. 72B, 722 and 722-1 across ref. 6241 production. The engraving on the movement is more reliable than a date-based attribution. Phillips and Sotheby’s catalogues also assign 72B, 722 and 722-1 to individual ref. 6240 watches dated circa 1965–1966. Those lot labels do not establish a serial-number changeover; read the movement engraving.

Cal. 722-1

Rolex-signed Valjoux 72-family movement, seventeen jewels — caliber sub-variant not distinguishable from the engraving alone

detail	value
type	Manual
complication	Chronograph
jewels	17
frequency	18,000 vph (2.5 Hz)
power reserve	48h
balance	Microstella (inherited from 722)
shock	KIF

Often dated to 1967, Cal. 722-1 was the last 18,000 vph Daytona caliber before Cal. 727 raised the frequency. Sotheby’s catalogues a circa-1965 ref. 6240 with 722-1; that lot attribution does not establish when Rolex first used the caliber. Rolex described it as a Valjoux 72A-based mechanism with the same dimensions as its predecessor; the changes were internal.

The hour-recorder conveyor gained an eccentric pivot and wing-shaped spring, allowing more precise engagement with the hour wheel. A guard spring above the balance was intended to keep the hairspring on its stud support under shock. Giussani records that the guard had already appeared inconsistently on Cal. 722 and caused problems of its own, so many surviving examples of both calibers lack it.

Cal. 727

Cal. 727 (right, engraved 727, Daytona ref 6265), specialist comparison photo via Perezcope

detail	value
type	Manual
complication	Chronograph
jewels	17
frequency	21,600 vph (3 Hz)
power reserve	48h
escapement	Swiss lever
balance	Microstella, adjustable inertia
shock	KIF

Cal. 727 raised the Valjoux 72 frequency from 18,000 to 21,600 vph and powered the refs. 6262, 6263, 6264 and 6265 from 1970 until 1988. A genuine example has a Breguet overcoil and a bevelled inner edge on the KIF shock-spring retaining ring. These details, together with the engraved caliber number, help distinguish an original movement from a substituted or counterfeit one.

Daytona chronograph (automatic)

Cal. 4030

Cal. 4030, engraved 4030, thirty-one jewels

detail	value
type	Automatic
complication	Chronograph
jewels	31
frequency	28,800 vph (4 Hz)
power reserve	52–54h (sources disagree)
balance	Free-sprung Breguet
escapement	Swiss lever

Launched with the ref. 16520 in 1988, Cal. 4030 was a heavily reworked Zenith El Primero 400 and the last externally designed movement used by Rolex. Rolex removed the date, reduced the frequency from 36,000 to 28,800 vph and changed more than half of the components. A Breguet overcoil replaced the flat hairspring, while a free-sprung Glucydur balance with Microstella regulation and KIF protection replaced the Zenith oscillator. The chronograph retained a column wheel and horizontal clutch.

Published power-reserve figures split between 52 and 54 hours, with no known Rolex document settling the difference. The photographed movement is signed "MONTRES ROLEX S.A. GENEVA SWISS, ADJ. 5 POSITIONS TEMPERATURE, THIRTY-ONE JEWELS" and stamped "4030."

Cal. 4130

Cal. 4130 movement detail, bridge marked "4130"

detail	value
type	Automatic
complication	Chronograph
jewels	44
frequency	28,800 vph (4 Hz)
power reserve	72h
escapement	Swiss lever, 52° lift angle
balance	Free-sprung, four gold Microstella nuts
shock	KIF

Cal. 4130 was developed and manufactured by Rolex for the ref. 116520 in 2000. Rolex history, 2000–2013 Its column wheel and vertical clutch avoid the hand jump reported for Cal. 4030 when the chronograph starts. The movement uses 201 components, about 20 per cent fewer than its predecessor, and twelve types of screw rather than more than forty.

The rotor runs on a ball bearing; the Cal. 3135 generation uses a jewelled sleeve. Claims that the bearing is ceramic lack support from Rolex or specialist documentation. The free-sprung balance sits under a transversal bridge and uses KIF protection. Chronergy, Paraflex, an optimised rotor bearing and Côtes de Genève arrived with Cal. 4131 in 2023. The display back also belongs to that successor and was limited to platinum; every Cal. 4130 Daytona has a solid caseback.

Parachrom was fitted from launch, but the blue version is variously dated between about 2005 and 2007 without a supporting Rolex document. Later examples were rated to Rolex's −2/+2 seconds-per-day standard after its introduction in 2015. Cal. 4130 continued through the ref. 116500LN until Cal. 4131 replaced it in March 2023.

Cal. 3230

detail	value
type	Automatic, no date
frequency	28,800 vph (4 Hz)
power reserve	Approximately 70 hours
escapement	Chronergy
hairspring / shock	Blue Parachrom / Paraflex
documented fitment here	124060, 124270, 126000, 126900; catalogue conflicts for some 114300 lots are recorded above

Rolex introduced Cal. 3230 in 2020 as the no-date member of its newer movement generation. Rolex describes the movement with a Chronergy escapement, blue Parachrom hairspring, Paraflex shock absorbers and approximately 70 hours of reserve. The individual reference page remains the authority for a specific watch; catalogue attributions that conflict with Rolex product documentation are recorded as conflicts rather than silently normalized. Rolex, History of Rolex, 2021

Cal. 3235

detail	value
type	Automatic, date
frequency	28,800 vph (4 Hz)
power reserve	Approximately 70 hours
escapement	Chronergy
hairspring / shock	Blue Parachrom / Paraflex
documented fitment here	Datejust, Sea-Dweller and Submariner Date families

Rolex introduced Cal. 3235 in 2015. It is the date-bearing member of the same generation as Cal. 3230, with a Chronergy escapement, blue Parachrom hairspring, Paraflex protection and approximately 70 hours of reserve. Rolex's brochures describe the date as instantaneous and the watch as COSC-certified and retested after casing to Rolex's tighter standard. Rolex, Datejust 41 brochure

Cal. 3255

detail	value
type	Automatic, day and date
frequency	28,800 vph (4 Hz)
power reserve	Approximately 70 hours
escapement	Chronergy
hairspring / shock	Blue Parachrom / Paraflex
documented fitment here	Day-Date 40 and Day-Date 36

Rolex introduced Cal. 3255 in 2015 for the Day-Date 40 and later Day-Date 36. The movement provides rapid-setting day and date displays, a Chronergy escapement, blue Parachrom hairspring, Paraflex shock absorbers and approximately 70 hours of reserve. It replaced Cal. 3156 in the Day-Date II successor generation; the 36mm Cal. 3155 remained a separate earlier movement. Rolex, History of Rolex, 2021 Rolex, Day-Date information sheet, 2022

Cal. 3285

detail	value
type	Automatic GMT
frequency	28,800 vph (4 Hz)
power reserve	Approximately 70 hours
functions	Independent rapid-setting local hour, 24-hour display, instantaneous date
escapement	Chronergy
hairspring / shock	Blue Parachrom / Paraflex
documented fitment here	GMT-Master II 126710, 126711, 126715, 126720 and related current references

Rolex introduced Cal. 3285 in 2018 for the GMT-Master II. Its GMT hand remains independent of the local hour, the date changes instantaneously, and the movement combines Chronergy, a blue Parachrom hairspring, Paraflex protection and approximately 70 hours of reserve. Rolex, GMT-Master II brochure

Cal. 4131

detail	value
type	Automatic chronograph
introduction	2023
power reserve	Approximately 72 hours
chronograph	Column wheel and vertical clutch
escapement / shock	Chronergy / Paraflex
documented fitment here	Daytona 126500 and 2023-onward gold and platinum Daytona references

Rolex introduced Cal. 4131 in 2023 as the successor to Cal. 4130. The movement keeps the column wheel and vertical clutch and adds the Chronergy escapement, Paraflex shock absorbers, a blue Parachrom hairspring and Rolex Côtes de Genève decoration. Rolex gives an approximately 72-hour reserve. Rolex Newsroom, Cosmograph Daytona

Cal. 4132

detail	value
type	Automatic chronograph
introduction	2023
special function	24-hour elapsed-time counter
documented fitment here	Daytona 126529LN, the Le Mans anniversary model

Cal. 4132 is the 4131 derivative used in the Le Mans anniversary Daytona. Rolex describes it as allowing the chronograph to count elapsed hours over 24 rather than the usual 12. The official history page does not publish a separate technical specification table, so the 4131 family specifications should not be copied into 4132 without a movement-specific source. Rolex, Cosmograph Daytona history

Day-Date

Day-Date calibers form their own family. Four-digit references set both calendar displays through the hands; five-digit references introduced quickset.

Cal. 1055

Cal. 1055, period parts-catalogue illustration, front and back

detail	value
type	Automatic
jewels	25
frequency	18,000 vph (2.5 Hz)
power reserve	42h
escapement	Straight-line lever
balance	Monometallic
shock	KIF

Cal. 1055 appears in catalogues for the first four-digit Day-Date references and is commonly dated 1956–1959. A 2017 Dorotheum listing pairs it with a 6511/8 dated circa 1965; Pergola’s unofficial chart places the case number in its 1956 band, and the lot photo has no readable serial. Treat the later date as an unresolved catalogue attribution. Cal. 1055 has rhodium-plated bridges with oeil-de-perdrix ("partridge-eye") circular graining rather than Côtes de Genève. Documented examples were adjusted to temperature and five positions.

Reference histories commonly date the 6611 to 1957 and associate it with the second, chronometer-certified 1055 generation. Phillips lists caliber 1055 on its 1956 gold 6611 and 1055B on its 1958 white-gold 6611B; catalogues do not use the suffix consistently. The dial wording changes to “Superlative Chronometer Officially Certified.”

6612 catalogues such as Phillips lot 43, Bonhams lot 353, and Monaco Legend lot 67 show the same naming problem: Phillips (1958 platinum case 403,680), Bonhams (circa-1959 gold 6612/8), and Monaco Legend (1958 6612B examples) list Cal. 1055, while Christie’s Dubai lot 65 uses B1055 and other catalogues use 1055B. Keep the calibre label attached to the specific watch and source; those descriptions do not establish that every 6612 retained its original movement.

For examples catalogued as 6612B, Monaco Legend lists Cal. 1055 on yellow-gold case 384,933, white-gold case 394,866 and platinum case 403,679. Phillips lists B1055 on platinum case 446,052; Christie's Dubai uses B1055 while listing the case as 446,062. Treat these as lot-specific catalogue labels. The Dubai case number conflicts with Phillips and Sotheby's, which both give 446,052. Monaco Legend, lot 182; Monaco Legend, lot 26; Monaco Legend, lot 67; Phillips, lot 155; Christie's Dubai, lot 65.

The arrival of the free-sprung Microstella balance is disputed. The usual account places it with the 66xx revision, but an auction description identifies a first-generation 6511 as free-sprung. Neither generation has quickset or hacking.

Steel school-watch records create a separate problem: Antiquorum lists 1556 for a 2002 lot and 1066 for a 2013 lot, while Phillips describes later steel Day-Date prototypes with 1555-series movements. These are catalogue descriptions of disputed school/prototype watches, not confirmed 6611 production fitments. See the 6611 record for the lot-level distinctions.

Auction catalogues disagree on the movement fitted to ref. 6511. Phillips lists Cal. 1555 for case 111,654, and Dorotheum lists Cal. 1555 for case 166736. Phillips lot 41, Antiquorum lot 81, Bonhams lot 156, Monaco Legend lots 22 and 220, and Dorotheum's 2017 lot for case 166744 list Cal. 1055. Phillips dates Cal. 1555 to 1959, later than the dates assigned to both 1555-labelled cases. The 2017 Dorotheum listing dates case 166744 circa 1965, while Pergola's unofficial chart puts the number in its 1956 band. Its front-view image offers no readable serial, leaving the two dates in conflict. Each entry is a catalogue attribution; keep it attached to its lot pending inspection of the movement.

Cal. 1555

Cal. 1555, rotor bridge detail

detail	value
type	Automatic
jewels	25
frequency	18,000 vph (2.5 Hz)
power reserve	42h
size	7.03mm
escapement	Swiss lever (Cal. 1530 train)
balance	Free-sprung beryllium-bronze, Microstella screws
shock	KIF Flector

Cal. 1555 powered early four-digit Day-Dates, including the refs. 1803, 1804, 1806, 1807 and 1811, from 1959 to about 1967. It combines the day-and-date architecture of Cal. 1055 with the plate and most running components of Cal. 1530. Its distinct parts are concentrated in the motion and calendar work, some shared with the contemporary Datejust Cal. 1575.

The Swiss lever escapement comes from Cal. 1530 and uses KIF Flector protection. The free-sprung balance uses a Nivarox Breguet overcoil and screw-shaped Microstella adjusters. Rolex did not adopt the later nut-shaped Microstella components until 1983.

Cal. 1555 does not hack; unlike the 1972 revision of Cal. 1556, its parts list has no balance-stop spring. Wear in the mainspring-barrel bearing is a known fault. As the plate and bridge bores wear out of round, the barrel can tilt and reduce amplitude; Rolex supplied a replacement upper barrel bush for the repair.

Five stainless-steel Day-Dates are publicly known, none with a listed reference or case serial. Christie's records movement numbers 0004547, 0005073, DD411420, DD14749 and DD081221. Their casebacks are signed Rolex and stamped "Stainless Steel"; the known examples have French day discs, black hands and silvered dials, with provenance linked to former Rolex watchmakers. Christie's identifies them as workshop test pieces. Movement DD411420 is engraved 1555 but runs at the Cal. 1556 frequency of 19,800 vph, placing it between the two generations.

The prototype's jewel count is disputed. Antiquorum gives 25, matching the bridge signature, while Phillips gives 26, the figure for Cal. 1556. At 7.03mm, Cal. 1555 is the thickest member of the 1500 series. The stepped "pie-pan" dial remained in use until about 1970, outlasting the caliber.

Cal. 1556

Cal. 1556

detail	value
type	Automatic
jewels	26
frequency	19,800 vph (2.8 Hz)
power reserve	42h
escapement	Swiss lever, 52° lift angle
shock	KIF Flector, both balance pivots

Cal. 1556 succeeded the 1555 around 1965 and powered the mid- and late four-digit Day-Date until 1977 or 1978. A revised gear train raised the frequency, while a jewel at the top of the centre wheel brought the count to 26. Its rhodium-plated movement has perlage finishing, a full balance bridge and a screwed balance with two gold, star-shaped Microstella regulating screws. Hacking was added during production in 1972 without a new caliber designation; earlier examples do not hack. Sotheby’s 2024 listing for ref. 1601 assigns Cal. 1556 to a watch described and photographed with a date-only dial. Rolex’s 1978 service manual defines Cal. 1556 as day-and-date, so this remains a catalogue conflict until the movement is inspected. Sotheby’s, lot 130.

Cal. 1566

detail	value
type	Automatic
jewels	26
escapement	Straight-line lever
balance	Monometallic, free-sprung Breguet spring

Cal. 1566 was built for one case, the platinum Day-Date 1831 commissioned for the Shah of Iran and delivered from 1977. The rhodium-plated movement has a free-sprung Breguet hairspring, Microstella regulation and hacking. Sources record either eight or nine examples. One concordance assigns the ref. 1831 to Cal. 1556, while auction houses that examined the watches identify Cal. 1566.

Cal. 3055

Cal. 3055, period parts-catalogue illustration with day-disc

detail	value
type	Automatic
jewels	27
frequency	28,800 vph (4 Hz)
power reserve	48h
escapement	Swiss lever
balance	Free-sprung Glucydur, Microstella
shock	KIF

Cal. 3055 powered refs. 18038, 18039, 18048, 18049, 18078, 18079, 18108 and early 18238 in the 1977–1988 generation. It introduced quickset for the date, while the day still advanced through the motion of the hands. The balance cock provides the usual visual distinction from Cal. 3155, which uses a full transversal bridge. Common references give a height of 6.3mm, but Rolex's parts diagram specifies 7.11mm.

Cal. 3155

Cal. 3155, engraved "3155," EmmyWatch

detail	value
type	Automatic
jewels	31
frequency	28,800 vph (4 Hz)
power reserve	48h
balance	Free-sprung Glucydur, Microstella
shock	KIF Elastor

Cal. 3155 replaced the 3055 in 1988 and remained in production through 2019. It added independent correction of the day, giving the Day-Date a double quickset for both calendar displays.

The added quickset works raised the jewel count from 27 to 31. Published height figures vary between 6.00 and 6.45mm, with no known Rolex document settling the discrepancy. As elsewhere in the 31xx family, a full bridge and larger balance wheel replaced the older balance cock.

The hairspring stud is laser-welded rather than glued as on Cals. 3035 and 3055. Parachrom arrived between 2008 and 2010 according to Grail Watch Reference, or by 2013 according to Watch Wiki. Cal. 3155 retained KIF Elastor throughout and never received Paraflex, which Rolex fitted to the Day-Date II's Cal. 3156.

Cal. 3156

Cal. 3156, engraved "3156," Day-Date II official brochure image

detail	value
type	Automatic
jewels	31
frequency	28,800 vph (4 Hz)
power reserve	48h
size	30.97mm
escapement	Swiss lever, 31xx family (pre-Chronergy)
balance	Parachrom hairspring (3155 base)
regulator	Free-sprung, gold Microstella nuts, traversing bridge
shock	Paraflex

Cal. 3156 is a widened Cal. 3155 derivative built for the 41mm Day-Date II from 2008 to 2015. It adds a Parachrom hairspring and Paraflex protection and powers the refs. 218238, 218239, 218206 and 218235. Its 30.97mm main plate carries the enlarged calendar wheels needed to move the date window outward. The same wider format appears on Cals. 3132, 3136 and 3187. Published specifications often give the standard 28.5mm width, but Rolex's promotional photography shows the additional flange recorded by Stephen Foskett's Grail Watch Reference.

Only the plate-and-bridge layer is oversized. The running train, escapement, keyless works and date mechanism use standard 31xx-family components, while structural parts such as the barrel bridge are shared with the wider Cals. 3132, 3136 and 3187 rather than the 3155.

The oscillator comes from Cal. 3155: a large free-sprung balance with gold Microstella nuts, a Breguet overcoil and a height-adjustable transversal bridge. Below it is the conventional Swiss lever escapement used across the 31xx family. Its 2015 successor, Cal. 3255, introduced the paramagnetic nickel-phosphorus Chronergy escapement. Rolex credits that design with a 15 per cent efficiency gain and about half of the increase from 48 to 70 hours of power reserve.

Cal. 3156 uses Paraflex shock protection; Cal. 3155 retains KIF Elastor. Rolex filed the design in 2005, and the European patent was granted in 2008. Its spring connects to the bearing body through four arms arranged around a central support, replacing the two-arm layout common to earlier systems. Rolex claims up to 50 per cent greater shock absorption than KIF; that is a manufacturer claim, not an independent test. Rolex patent US7234859B2

Cal. 3156 was confined to the 41mm Day-Date II. Rolex retired both in 2015, replacing them with the 40mm Day-Date and Cal. 3255, while the 36mm Cal. 3155 remained in production until 2019. Most Cal. 3156 watches carried the COSC −4/+6 seconds-per-day standard. Rolex adopted its −2/+2 rating in the caliber's final year, 2015.

Oysterquartz

Secondary collector references place total Oysterquartz production just under 25,000 watches, but no factory production total is cited here. The line followed the Beta 21-powered ref. 5100 of 1970, developed through the Centre Electronique Horloger consortium. The Beta 21 would not fit an Oyster case. Rolex left the consortium in 1972 and spent five years developing Cals. 5035 and 5055 in-house.

Cal. 5035

Cal. 5035, engraved "5035," "11 ELEVEN JEWELS," "1.55V," EmmyWatch

detail	value
type	Quartz
jewels	11
frequency	32,768 Hz crystal
drive	Mobile-frame step-by-step motor, pallet fork, 1 beat/s
circuit	C-MOS module: oscillator, binary divider, impulse amplifier
rate adjustment	Trimmer, about 2 s/d total range
battery	1.55V silver-oxide, 24+ months
size	29.75mm diameter (29.00mm case-fitting), 6.35mm high

Cal. 5035 powered Oysterquartz Datejust and Oyster Perpetual references, including the 17000, 17013 and 17014, from 1977 to 2001. Its date mechanism follows the same principle as the mechanical Cal. 3035 introduced in the same year.

Rolex calls the drive a mobile-frame step-by-step motor. Unlike a conventional quartz stepper, its coil moves while the magnets remain fixed. A polarised pulse swings the coil frame once per second, and a finger on the frame drives a pallet fork connected directly to the seconds wheel. The pallet locks the wheel between pulses. Its audible tick comes from that engagement and sounds closer to a mechanical escapement than a conventional quartz motor.

The C-MOS module contains the oscillator, a binary divider that reduces 32,768 Hz to one pulse per second, and the motor's impulse amplifier. A trimmer provides a total adjustment range of about two seconds per day. Rolex specified regulation to ±0.05 seconds per day at about 28°C.

Temperature compensation remains uncertain. Secondary accounts describe a thermocompensated oscillator with a thermistor, but Rolex's technical document mentions neither. It instead shows a parabolic rate curve with an inversion point at 26 ±2°C and specifies adjustment near the 28°C temperature of a worn watch. The document may predate a later revision, but it does not support the usual thermistor claim.

Rolex specified accuracy within one minute per year under normal wear and battery life beyond 24 months. The movement draws no more than 9 microamps, of which the electronics use at most 3. There is no battery end-of-life indication; erratic running is the warning. Hacking cuts current to the motor, and the seconds hand restarts one second after the crown returns to its running position.

The electronic module and motor are sensitive to contamination, and the mobile-frame pivots run dry. Rolex supplied the motor only as a complete unit rather than as separate components.

Cal. 5055

Cal. 5055, engraved "5055," "11 ELEVEN JEWELS," EmmyWatch

detail	value
type	Quartz
jewels	11
frequency	32,768 Hz crystal
drive	Mobile-frame step-by-step motor, pallet fork, 1 beat/s
circuit	C-MOS module: oscillator, binary divider, impulse amplifier
rate adjustment	Trimmer, about 2 s/d total range
battery	1.55V silver-oxide, 24+ months
size	29.75mm diameter (29.00mm case-fitting), 7.11mm high

Cal. 5055 is the Day-Date counterpart to Cal. 5035. The two share their motor and electronic module, while the 5055's calendar follows the principle of the mechanical Cal. 3055. Its day-disc stack increases the height from 6.35 to 7.11mm.

Catalogue descriptions treat Cal. 5055 as COSC-certified from early production. The exact certification and crystal changeover dates for Cal. 5055 and Cal. 5035 are not settled in the sources reviewed, so early Oysterquartz dial text should be checked against the individual watch.

Cal. 5055 adds the day mechanism and its stricter tolerances. Rolex specified hour-wheel endshake below 0.03mm and calendar change within two minutes of midnight. The day disc is a separate replaceable part, allowing the display language to be changed without altering the movement.

Cal. 5055 powers the yellow-gold ref. 19018, white-gold ref. 19019 and pyramid-bezel ref. 19028. Claims about cancelled successor calibers are omitted because the cited factory material does not document them.

Related but not Rolex

Gruen Cal. 877 and the Bubbleback-era "9¾ ligne" description are often misidentified as Rolex calibers. Gruen's Cal. 877, used in the Techni-Quadron, is an Aegler-built architectural sibling of Cal. 300 sold under Gruen's name in the United States. It was never a Rolex commercial number. A Bubbleback-era "9¾ ligne" description records only the movement's size class, not a distinct caliber designation. The three circa-1940 Christie’s ref. 3064 catalogues reviewed for this audit use the same size-class wording and do not name a caliber; keep the 3064 movement attribution tied to those lot descriptions.

Sources

• Watch LIFE News / LowBEAT, “Rolex’s simple hand-wound models” (Japanese), 22 August 2022
• EveryWatch archive of Bonhams 2012 lot 127, ref. 2280 case 79,895
• Watch-Wiki, Cal. 1570 list, ref. 1022 entry (1965–1974)
• Pergola serial chart photograph, unofficial year bands
• Waddington’s, ref. 1023/8B, Cal. 1570
• Hess Fine Auctions, ref. 1023 lot 12570, Cal. 1570
• Watch.de archive, ref. 1023, Cal. 1570
• Rolex Forums, 2022 ref. 1023 listing and movement photograph
• Gardiner Houlgate, 20 May 2025, lot 73, ref. 1023, Cal. 1560
• Kaplans Auktioner, 2 October 2021, ref. 1023 serial 2186841, Cal. 1570
• Time Connection II, ref. 1023 replacement-parts row
• Christie’s, ref. 6556, case 138'822, Cal. 1040
• Aaron Berlow, Cal. 1040 restoration, Hodinkee, 2015
• Hodinkee, ref. 6556 dial and service observations, 2016
• Antiquorum, ref. 6556 and proposed ref. 1020, 2012
• Dr. Crott, 86th auction catalogue, Tru Beat model history, 2012; calls 1020 a new caliber
• The Vintage Rolex Field Manual, printed p. 162, Oyster Perpetual reference table, ref. 1020
• Dr. Crott, ref. 6556 and proposed ref. 1020, 2019
• Phillips, ref. 6556, 18K gold, Cal. 1040
• Phillips, ref. 6556, Cal. 1040 and steel case
• Antiquorum, ref. 6556/0, Cal. 1040, 2020
• Antiquorum, ref. 6556, Cal. 1040, 2021
• David Boettcher, “Oyster Watch Co.”; FHF 30 and Tudor Cal. 59/59SC

• Sotheby's, ref. 6609, circa 1956, Cal. 1065
• Christie's, ref. 6609, circa 1956, Cal. 1066
• Antiquorum, ref. 6609 case 447272, Cal. 1066
• Phillips, ref. 6609 emblem-dial example, catalogued Cal. 1030
• Monaco Legend, ref. 6609 case 280389, Cal. 1065
• Phillips, ref. 6609 case 355605, Cal. 1065
• Antiquorum, ref. 6567, 1956, Cal. 1030
• Antiquorum, 2000, ref. 6564, Cal. 1050
• Ineichen, 2025, ref. 6567, Cal. 1050
• Bonhams, 2015, ref. 6569, Cal. 1050
• Christie's, circa 1955, Submariner ref. 6536/1, Cal. 1050
• Adams, ref. 1022, 2025, Cal. 1560
• Bonhams, ref. 1022, 2015, Cal. 1560
• Pandolfini, ref. 1022, 2014, Cal. 1560
• Tajan, ref. 1022, 2014, automatic movement; caliber not stated
• HODINKEE Shop, ref. 1022, 1963, Cal. 1560
• Sotheby’s, 2023, Prince Imperial 1645, lot 331
• Antiquorum, 2022, Prince Imperial 1645, lot 321
• Antiquorum, 2006, Prince Imperial 1645, lot 16
• Antiquorum, 2019, Prince Imperial 1645, lot 31
• Antiquorum, 2012, Prince Imperial 1645, lot 70

• Phillips, 2015, ref. 6511 case 111,654, movement listed as 1555
• Dorotheum, 2026, ref. 6511 case 166736, movement listed as 1555
• Dorotheum, 2017, ref. 6511/8 case 166744, movement listed as 1055
• Phillips, Cal. 1555 chronology and experimental steel Day-Date
• Phillips, 2015, ref. 6511 case 134,692, movement listed as 1055
• Phillips, 2015, 6611 case 214,124, caliber 1055
• Phillips, 2015, 6611B case 401,546, caliber 1055B
• Antiquorum, 2002, steel school watch catalogued as 6611, caliber 1556
• Antiquorum, 2013, steel school watch catalogued as 6611, caliber 1066
• Phillips, 2021, steel Day-Date prototype account

• Christie’s, lot 52: 8171 case 685878, A.295 CPL
• Giorgia Mondani, Fratello, 2020: case construction and calendar correctors
• Christie’s: 6062 case 916321, caliber 655
• Aste Bolaffi, ref. 1858 lot 34 — movement no. 1143 identified as Hunter 8¾ (520)
• WatchNet Japan, product A-6378 — seller-attributed Cal. 520 Antiquorum, ref. 6006, lot 253
• Vintage & Prestige, stock W2107 — seller-listed Cal. 520 / 8¾
• Anthony Traina, Hodinkee, “The Rolex Bubbleback and Why It Still Matters”, 7 October 2024 — movement-family account

• Watch Doctor: movements and calibers chart. Secondary compilation; no underlying Rolex document identified.
• Incabloc: company history, production in 1933 and lyre-spring development in 1938.
• Rolex: Technical and Service Information, third edition, pp. 3 and 7; scan hosted by the Vintage Rolex Field Manual.
• Sotheby’s Geneva 2025, lot 134: Gleitze Oyster and its upgraded movement.
• COSC: organization established in 1973.
• Rolex: examination and estimate before servicing.

• Rolex: Perpetual rotor, mechanism introduced in 1931; caliber not specified.
• Antiquorum Geneva, 16 November 2002, lot 486, ref. 4467 catalogued with Cal. 740 and a date display.
• Rolex: Explorer history, return to 36mm in 2021.
• Rolex GMT-Master II user guide, date linked to the independently adjustable local-hour hand.
• Sotheby's, circa-1958 6542, calibre 1030
• Sotheby's, circa-1959 6542, case 451'698, calibre 1066
• Christie's, circa-1959 gold 6542, case 486'469, calibre 1065

• Revolution — A Movement in History: The Zenith-driven Rolex Daytona (Ross Povey, 2018)
• Hodinkee — A Vintage Watch Nerd's Critical Dissection of the Rolex Daytona, Part 1 (Paul Boutros, 2012)
• Hodinkee — A Vintage Watch Nerd's Critical Dissection of the Rolex Daytona, Part 2 (Paul Boutros, 2013)
• Monochrome — In-Depth: The History of the Rolex Daytona (Erik Slaven, 2024)
• Monochrome — History of the Rolex Submariner, Part 1 (Tom Mulraney, 2020)
• Monochrome — History of the Rolex Submariner, Part 2 (Tom Mulraney, 2020)
• Monochrome — In-Depth: The History of the Rolex GMT-Master and GMT-Master II
• Monochrome — The History of the Rolex Explorer (Frank Geelen, 2024)
• Monochrome — In-Depth: The History of the Rolex Explorer II
• Monochrome — Youngtimer Case Study, the Rolex Explorer 14270 (Frank Geelen, 2020)
• Monochrome — Rolex Explorer 214270 In-Depth Review (Brice Goulard, 2016)
• Hodinkee — A Comprehensive Collector's Guide To The Rolex Explorer I (Jon Bues, 2022)
• WatchTime — Tracking the Rolex Daytona: A 55-Year History
• Revolution — The Rolex "John Player Special" Paul Newman Daytona Ref. 6241 (Bob Ridley, 2017)
• A Collected Man — Is the Rolex Pre-Daytona a Forgotten Classic? (Russell Sheldrake, 2020)
• Fratello — Why I Bought The Rolex Cosmograph Daytona Reference 116520 (Ben Hodges, 2021)
• Fratello — Rolex Submariner 14060M Review
• Fratello — Rolex Submariner 114060 Review (2019)
• Fratello — Ceramic Bezel close-up of the Rolex GMT-Master II ref. 116710LN
• Sotheby's — Submariner Ref 6536/1, Stainless Steel Automatic With Bracelet, Circa 1957
• Sotheby's — Submariner Ref. 6538, Stainless Steel With 4-Line Tropical Dial, Circa 1958
• Caliber Corner — per-caliber technical database
• Grail Watch Wiki — Rolex 630
• EmmyWatch — vintage restoration movement photography
• Monochrome — Complete History of the Rolex Milgauss
• Christie’s, ref. 6543 case 145'111, Cal. 1080
• Christie’s, ref. 6543 case 145'159, Cal. 1065
• Revolution, Milgauss movement and 6543 history
• Stephen Foskett, Watch-Wiki Cal. 1080 reference index for 6543
• Sotheby’s, 6541 case 412'479, Cal. 1080
• Phillips, same case and movement number, Cal. 1055
• Robb Report — The Most Expensive Rolex Watches Ever Sold at Auction (Sotheby's Mercedes Gleitze Oyster, November 2025)
• Antiquorum — auction lot catalogue
• Christie's — auction lot catalogue
• Heritage Auctions, ref. 3136 case 105063, FHF 30 / Cal. 59
• Waddington's, ref. 3136 case 147396, Cal. 59
• Sotheby's — auction lot catalogue
• Watch Wiki — reference concordance
• Montres Rolex SA — Technical Information No. 13: Calibre 5035 / Calibre 5055 (factory service documentation, scan hosted by The Vintage Rolex Field Manual)
• Oysterquartz.net — the 5035/5055 movement
• Rolex — Reversing Wheels, Watchmaking Features (red anodised-aluminium finish, introduced 1957)
• Rolex — Superlative Chronometer Certification: Redefining Performance (brochure, 2024; certification redefined 2015)
• Patent US6503341B2 — Self-compensating spiral for a spiral balance-wheel (Montres Rolex SA; Jacques Baur and Patrick Sol; priority 1999, granted 2003 — the Parachrom hairspring)
• Patent US7234859B2 / EP1705537 — Shock-absorbing bearing for a timepiece (Montres Rolex SA; Mitchell Colle and Roman Voirol; priority 2005 — Paraflex)
• SJX Watches — Explained: The Rolex Parachrom Hairspring (Nb-Zr alloy, anodised oxide layer, frequency shift)
• Grail Watch Reference — Rolex Cal. 3136 (Stephen Foskett; Paraflex fitted to the 3136 and not to the base 3135)
• Caliber Corner — Rolex Caliber 3131 (Kif on the 3131, Paraflex on the 3132)
• Superlative Time — Identification of Rolex Calibres 1520–1580 (balance-bridge forms 1–4; Kif Flector and Kif Elastor assignment)
• NAWCC message board — Regulate Rolex 1520 (watchmakers on the inertia-block system and the free-sprung misreading)
• Vintage Rolex Forum — History of the 1530 movement (introduction c.1957, butterfly rotor, chronometer status)
• Watch Repair Talk — Rolex 3135-510 ratchet drive wheel wear
• Antiquorum Geneva, 3 April 2025, lot 219: ref. 3121 Oyster Grenfell, case 43,475, circa 1938, Cal. 59, 17 jewels.
• TimeAnagram, item 7507: ref. 3121 listed as manual Cal. 710; the movement image shows no readable caliber stamp.
• The Vintage Rolex Field Manual — Colin A. White, Morning Tundra
• Rolex Cal. 1560 spare-parts sheet no. 31; scan hosted by WatchGuy
• The Vintage Rolex Field Manual, printed p. 74, chronograph table
• Christie’s, model 1074, 1920s example
• Christie’s, ref. 1074, case 25433
• Christie’s, case no. 1223 monopusher
• Christie’s, ref. 28D1 pocket chronograph, movement no. 1223

• Antiquorum Geneva, 2014, ref. 6075 case 714441: catalogued as A.295, with a 10½-ligne description.
• Phillips Geneva, 2015, ref. 6075 case 714440: catalogued as A.296, 18 jewels.
• Christie’s, ref. 6075 case 699455: catalogued as A.295.
• Morton Subastas, ref. 1024, 2024, Cal. 1560
• Waddington's, ref. 1024, 2024, Cal. 1560
• Dorotheum, ref. 1024, 2018, Cal. 1570
• Phillips, ref. 1024, 2021, Cal. 1570
• Antiquorum, ref. 1010/1011, 1960, Cal. 1560, case 576171
• Antiquorum, ref. 1010/1011, 1962, Cal. 1560, case 933961
• Heritage Auctions, ref. 1010, circa 1962, Cal. 1560, case 646320
• Bonhams, ref. 1010, circa 1967, Cal. 1560, case 1659430
• Antiquorum, ref. 1010, circa 1968, Cal. 1570, case 1,960,000
• 1stDibs item text: claimed ref. 1010, Cal. 1560; title says ref. 1011
• Antiquorum, ref. 1011, 1960, Cal. 1560, case 546423
• Christie’s, ref. 1011 case 692498, circa 1962, Cal. 1570
• Heritage, ref. 1011, Cal. 1560, 2012
• Waddington’s, ref. 1011, Eaton’s presentation dial, Cal. 1520
• Antiquorum Milan, 1996 Eaton’s ref. 1011, Cal. 1530
• Loupe This lot 2475, photo of Cal. 1530 in case marked 1011
• Antiquorum Geneva, 2004, Eaton’s ref. 1011, 17-jewel Cal. 1530
• Antiquorum New York, 2003, Eaton’s ref. 1011, Cal. 1520
• Antiquorum New York, 2011, Eaton’s ref. 1011, 26-jewel Cal. 1530
• Antiquorum New York, 2007, Eaton’s ref. 5590/1011, Cal. 1530
• Finarte Milan, 2024, Eaton’s ref. 5590-1011, Cal. 1530
• Antiquorum, ref. 6094/6294, 2008, lot 530
• Antiquorum, ref. 6094, 2010, lot 134
• Antiquorum, ref. 6094, 2012, lot 291
• Antiquorum, ref. 6094, 2018, lot 138
• Antiquorum, ref. 1768 case 019784, 2017: 7½-line T.S. 300 listed with 15 jewels
• Uhren-Muser, ref. 1768 case 019794, 2023: photographed Extra Prima marked 17 Rubies

• Rolex Technical and Service Information, third edition (1978), Cal. 1600
• Farsetti, ref. 3735, lot 107363
• Fortuna, ref. 3735, lot 113
• Watch-Wiki, Cal. 1570 reference list, including 1022
• Time Connection II, 1022 case-parts row listing Cal. 1560 and 1570
• LV800 via 1stDibs, ref. 1022, case 856242, Cal. 1560, 26 jewels
• Master of Time, Viceroy ref. 1573, dealer-attributed Cal. 600
• Rolex Cal. 1565 parts catalogue, Rolex technical department
• Rolex Cal. 1575 parts catalogue, Rolex technical department
• Phillips, HK Auction NINE lot 903, exterior ref. 6558 / inner stamp 6556, Cal. 1040
• Antiquorum Geneva 2006, ref. 6082 case 784516, Cal. 710
• Antiquorum Hong Kong 2021, ref. 6082 case 721396, Cal. 710
• Monaco Legend 2023, ref. 6082 case 810693, Cal. 710
• Colin A. White, The Vintage Rolex Field Manual, reference table: 6082 / Cal. 710
• Kibble Watches, concentric-dial ref. 6082 listing, seller identifies Cal. 1210
• Watch.de archive, ref. 6082 case 721965, seller identifies Cal. 1210
• Heritage Auctions, ref. 1013 case 488087, circa 1957, Cal. 1560
• Antiquorum, ref. 1013 case 952437, circa 1962, Cal. 1560
• Monaco Legend Auctions, ref. 1013 case 1,368,354, 1966, Cal. 1570
• Gazette Drouot, ref. 1013, circa 1968, Cal. 1570
• Rago, ref. 1013 serial 5,266,934, 1978, Cal. 1570
• Hodinkee Shop, ref. 6108 case 803948
• Heritage Auctions, 2012, lot 74039, ref. 6108 case 803752
• Antike Uhren Eder, ref. 6108 item 7140rol

• Heritage Auctions, ref. 3351 Regent, case 118141, Cal. 59
• Dawsons, ref. 3351 Lincoln, serial 170648, Cal. 59
• Wanna Buy A Watch, ref. 3351 Standard, Cal. 59
• AntiWatchman, ref. 3351 Regent movement photograph
• Darlor, dealer-described 3351-F, serial 118,489, Cal. 59
• Christie's, ref. 3351 Extra Precision, Extra Prima
• Christie's, ref. 116758 SARU, circa-2006, Cal. 3185 attributed
• Christie's, ref. 116758 SARU, circa-2007, Cal. 3185 attributed
• Sotheby's, ref. 116758 with SARU bezel, circa-2007, Cal. 3186 attributed
• Phillips, ref. 116758 SARU, circa-2009, Cal. 3186 attributed
• Christie's, ref. 116758 SARU, circa-2010, Cal. 3186 attributed
• Rolex USA, 2008 catalogue, 31-jewel chronometer specification without calibre number