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{{DISPLAYTITLE:Rolex 2940 Bubbleback}}
{{#seo:
{{#seo:
|title=Rolex Oyster Perpetual "Bubbleback" 2940 — BezelBase
|title=Rolex Bubbleback 2940 (1940–1949) — Production & Dial Guide | Rolexopedia
|description=The 2940 is the wartime Bubbleback. Introduced around 1940 and produced through 1949, it spans the years when Swiss watch production had to keep running…
|description=Reference guide to the Rolex Bubbleback 2940, a 31–32mm two-piece Oyster with center seconds, documented steel and gold-top cases, and 1940s dial variants.
|keywords=Rolex, 2940, Bubbleback, specifications, reference guide
|image=Ref 2940 hero.webp
|type=article
|image_alt=Rolex 2940 Bubbleback steel 1942
|type=Article
|og_type=article
|published_time=2026-04-17T22:14:06Z
|modified_time=2026-08-04T00:11:36Z
|robots=index,follow,max-image-preview:large
}}
}}


<small>[[Reference:bubbleback|Bubbleback]] › '''2940'''</small>


<small>[[Reference:bubbleback|Bubbleback]] → '''2940'''</small>
<div class="rp-lead">
[[File:Ref 2940 hero.webp|thumb|center|640px|alt=1942 steel Bubbleback|1942 steel Bubbleback]]
</div>


The 2940 is the wartime Bubbleback. Introduced around 1940 and produced through 1949, it spans the years when Swiss watch production had to keep running while Europe burned, and the commercial catalog had to keep selling while most of its traditional markets closed. Rolex met the moment with a two-piece Oyster that kept to the form the 3131 established four years earlier but pushed it toward volume production in steel. Where the 3131 was a precious-metal statement reference, the 2940 was the version that went to war — stainless steel, center sweep seconds, and a dial catalog wide enough to suit whatever market still took delivery. It is also the reference that sits at the center of the “hooded lug” forgery problem that continues to haunt Bubbleback authentication.
The 2940 is a 31–32mm two-piece Bubbleback with center seconds. Published examples include stainless-steel, gold-top and 9K cases, with dial variants documented across 1940s auction and specialist records.


<span id="core-facts"></span>
<span id="core-facts"></span>
== Core facts ==
==Core facts==
 
{| class="wikitable rp-facts"
{| class="wikitable"
|-
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! detail
! detail
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|-
|-
| production
| production
| c.1940–1949 (peak 1942–1947)
| c.1940–1949; many cited examples date to 1942–1947
|-
|-
| case diameter
| case diameter
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|-
|-
| movement
| movement
| Cal. 9¾’’’, 17 jewels (some 18j); some examples Cal. 630
| Cal. 9¾′′′, 17 jewels (some 18j); some examples Cal. 630
|-
|-
| case materials
| case materials
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<span id="where-it-sits-in-the-line"></span>
<span id="where-it-sits-in-the-line"></span>
== Where it sits in the line ==
==Where it sits in the line==
The 2940 is a center-seconds Bubbleback that followed the two-piece case introduced by the 3131 and 3132. Its center-mounted seconds hand runs from the 9¾′′′ movement family rather than a subsidiary register at 6. Published records place production roughly from 1940 through 1949, with many cited examples dated 1942–1947.


The 2940 is the volume wartime Bubbleback. The 3131 and its sweep-seconds twin 3132 had proven in 1936 that the two-piece Oyster could be manufactured at scale; the 2940 is the reference that made the same case architecture available in steel and inexpensive gold cap. It carries the sweep-seconds configuration that the 3132 pioneered — a center-mounted seconds hand running off Cal. 9¾’’’ rather than a subsidiary register at 6 — and pairs it with a case sized for a masculine wartime wrist. Production runs from roughly 1940 through 1949, with the concentrated peak falling in the five years from 1942 through 1947.
[[File:Ref 2940 full.webp|thumb|right|250px|alt=2940 rose-numeral dial Phillips lot|Phillips Geneva 2015 lot, rose-numeral dial]]
 
Within the Bubbleback range, the 2940 sits beside the sub-seconds 2764, the more mixed-metal 3065, and the engine-turned 3372. Steel, gold-top over steel, and 9K solid-gold cases are documented; the cited records do not establish production proportions. The documented serial range runs from the low 200,000s to the high 600,000s, which fits roughly 1942 to 1949. Unlike later sports references, the 2940 does not break into neat generations. The variation is in dials, hands, and case metal.
Within the broader Bubbleback family, the 2940 sits alongside the sub-seconds 2764, the steel-and-precious 3065 with its hooded lugs, and the 3372 with its engine-turned bezel. Steel 2940s carry the most examples; the 14K gold-top/steel configuration sits above them in the hierarchy, with solid 9K gold examples the scarcest of the three materials. Earliest surfaced serials run in the low 200,000s, consistent with 1942 production; the latest documented examples push into the high 600,000s, consistent with 1949. The reference does not evolve in generational tiers the way a later Submariner does. Variation happens in dials, hands, and the metal the case was cut from.


<span id="the-wartime-commercial-position"></span>
<span id="the-wartime-commercial-position"></span>
=== The wartime commercial position ===
===The wartime commercial position===
 
The early 1940s records show the 2940 in more than one market. Dial and case combinations vary across the surviving examples, but the cited sources do not establish how Rolex allocated production by market.
The early 1940s were an unusual commercial window for Rolex. Switzerland’s neutrality kept production running through a period when most other European watchmakers were either shuttered or converted to military work. German and Italian markets closed; Allied markets opened unevenly. Rolex responded by pushing export into the markets that remained — the UK (which took solid 9K gold and gold-top/steel Bubblebacks in volume), neutral-nation retailers, and later the US through increasing wartime American interest. The 2940’s dial variety tracks that commercial spread. Sector dials, California dials, Arabic-radium dials, 24-hour military dials, and retailer-signed dials all surface on 2940 cases, and that breadth is not typical for a single reference in a single decade. It reflects Rolex’s willingness to configure a Bubbleback however a given retailer or market wanted it.


<span id="the-two-piece-case"></span>
<span id="the-two-piece-case"></span>
== The two-piece case ==
==The two-piece case==
The 2940 uses the two-piece case architecture the 3131 introduced in 1936: a round mid-case with the bezel integral to the case middle, closed at the back by a screw-down caseback that threads directly into the case. The case has no separate bezel ring or discrete movement-holder. It measures 31–32mm in diameter with a lug-to-lug of roughly 38–38.5mm and a lug width between 16 and 17mm. The bezel is smooth and domed, polished, unmarked, set slightly proud of the crystal aperture.


The 2940 uses the two-piece case architecture the 3131 introduced in 1936: a round mid-case with the bezel integral to the case middle, closed at the back by a screw-down caseback that threads directly into the case. No separate bezel ring. No discrete movement-holder. The case measures 31–32mm in diameter with a lug-to-lug of roughly 38–38.5mm and a lug width between 16 and 17mm. The bezel is smooth and domed — polished, unmarked, set slightly proud of the crystal aperture.
The inner lug profile is squared-off. This is the standard 2940 lug configuration, and it is the reference point for checking a hooded-lug claim.
 
The inner lug profile is squared-off. This is the standard 2940 lug configuration, and it is the key reference point for the hooded-lug authentication problem that the reference carries.


[[File:Ref 2940 profile.webp|thumb|right|250px|alt=2940 Bubbleback profile bulge|1946 example, profile shows Bubbleback caseback bulge]]
<span id="the-hooded-lug-debate"></span>
<span id="the-hooded-lug-debate"></span>
=== The hooded-lug debate ===
===The hooded-lug debate===
Published Bubbleback references associate the hooded-lug case form with the 3065 rather than the 2940. A 2940 offered with hooded lugs therefore needs close comparison of caseback stamping, lug geometry and provenance before the reference is accepted.


A certain number of 2940s surface in dealer listings with hooded lugs — extended “teardrop” lug profiles that sweep down and around the case to cover the spring bar area. Hooded-lug Bubblebacks are a documented Rolex configuration, but they are properly the province of ref 3065, not ref 2940. The VRF collector consensus, echoed on TimeZone, RolexForums, and specialist forum threads, is that 2940s appearing with hooded lugs are almost invariably aftermarket modifications: a 2940 case extended with welded or resoldered lug material to impersonate the rarer and more commercially desirable 3065. The authentication points are caseback stamping (which should read 2940, not 3065, on a genuine 2940), the precise geometry of the lug-to-case transition (which reveals tool marks on modified examples), and the proportions of the hood itself relative to the case middle. Dealer listings on 1stDibs and comparable platforms occasionally present 2940/hooded-lug examples as authentic; the specialist collector literature does not accept them.
A hooded-lug 2940 claim needs positive evidence. The cited collector record does not establish a confirmed original 2940 with that case form.
 
When a 2940 appears for sale with hooded lugs, the presumption is modification. The burden is on the seller to demonstrate otherwise, and the published collector record does not contain a documented example where that demonstration has succeeded.


<span id="serial-and-reference-engraving"></span>
<span id="serial-and-reference-engraving"></span>
=== Serial and reference engraving ===
===Serial and reference engraving===
 
2940 cases carry the reference number engraved between the upper lugs and the serial number engraved between the lower lugs, consistent with the 1920s–1940s Oyster convention. Caseback interiors carry the Oyster Watch Co. signature along with period-correct patent and hallmark markings. The reference is also repeated on the caseback interior. This double-engraving of the reference makes 2940 authentication relatively straightforward where the lugs have not been altered; forged-hood examples can be detected by comparing the between-lug engraving (still typically legible as 2940) against the lug profile (incorrectly modified to a hooded form).
2940 cases carry the reference number engraved between the upper lugs and the serial number engraved between the lower lugs, consistent with the 1920s–1940s Oyster convention. Caseback interiors carry the Oyster Watch Co. signature along with period-correct patent and hallmark markings. The reference is also repeated on the caseback interior. This double-engraving of the reference makes 2940 authentication relatively straightforward where the lugs have not been altered; forged-hood examples can be detected by comparing the between-lug engraving (still typically legible as 2940) against the lug profile (incorrectly modified to a hooded form).


<span id="the-movement"></span>
<span id="the-movement"></span>
== The movement ==
==The movement==
 
The 2940 runs on Rolex's 9 3/4 ligne automatic family, usually 17 jewels and sometimes 18 in better-grade or later-service examples. The practical point is simple: this is a Bubbleback-era automatic with center sweep seconds, not a special one-off movement.
The 2940 runs on Rolex’s 9¾’’’ automatic caliber family, with 17 jewels in most documented examples and 18 jewels cited occasionally by sources that appear to refer to higher-grade or service-replacement variants. The base movement is an evolution of Cal. 620 with the indirect-drive sweep seconds mechanism that characterizes Cal. 630. It runs at 18,000 beats per hour, carries a straight-line lever escapement, a Breguet-style hairspring, and shock protection in the later production examples. The plating is rhodium, standard for the era. Winding is automatic and unidirectional through the 360-degree rotor — the rotor spins freely in one direction and engages the winding gear in the other, which is what gives the Bubbleback its case-back dome.


The 2940’s movement is non-hacking. Pulling the crown to the setting position stops the hands from advancing but the seconds continue to sweep; setting to the exact second requires a fractional backlash adjustment that is second nature on contemporary vintage Rolex but foreign to any Rolex made after the introduction of hacking seconds in the 1970s.
The cited 2940 movements do not have a documented hacking feature. Pulling the crown stops the hands while the seconds continue to run, so exact synchronization requires a small setting correction.


Cal. 630 is cited on some 2940 examples and is the formal numbered caliber for the 9¾’’’ sweep-seconds configuration. The two designations refer to the same movement family under different naming conventions: the ligne measurement (9¾’’‘) is older, and the numbered caliber (630) is the catalog reference Rolex used in service documentation. A 2940 described with Cal. 9¾’’’ and a 2940 described with Cal. 630 are, in practice, the same watch.
Cal. 630 is cited on some 2940 examples as the numbered designation for the 9¾′′′ sweep-seconds configuration. Other catalogues give only the ligne measurement. The movement and its markings should be inspected on each watch rather than inferred from the reference alone.


<span id="dial-variants"></span>
<span id="dial-variants"></span>
== Dial variants ==
==Dial variants==
 
The 2940 has a broad documented dial range. Some of this breadth reflects Rolex's pre-war practice of configuring dials to retailer specification; some of it reflects the reference's long production run across multiple export markets; some of it reflects refinishing activity over the subsequent eight decades.
The 2940 carries the widest dial catalog of any Bubbleback reference. Some of this breadth reflects Rolex’s pre-war practice of configuring dials to retailer specification; some of it reflects the reference’s long production run across multiple export markets; some of it reflects refinishing activity over the subsequent eight decades.


'''Sector dial.''' A multi-tone silver sector dial with dot and Arabic indices, divided into concentric or radial zones. Rare on the 2940. The sector dial is one of the signature 1940s Rolex dial configurations and surfaces occasionally on 2940 cases, where it carries a significant premium over the standard silvered or black dial.
[[File:Ref 2940 dial-detail.webp|thumb|right|250px|alt=2940 dial close-up rose numerals sub-seconds|Applied rose numerals + sub-seconds register]]
The sector dial, multi-tone silver with dot and Arabic indices divided into concentric or radial zones, appears less often in the cited 2940 record. The sector layout appears on some 2940 cases; the cited auction record does not establish a general price premium.


'''California dial.''' The California dial — Roman numerals on the upper half, Arabic numerals on the lower half, with a square marker at 6 — appears on the 2940 both as original Rolex production and as later refinishing. The Phillips Geneva Watch Auction TWO 2015 Lot 277 example is the best-documented original-production California 2940: stainless steel case, pink California dial, dated c.1941, estimated CHF 8,000–12,000 and sold at CHF 10,000 on the low estimate. Original-production California dials on 2940 cases are scarce; refinished California dials on 2940s are common and trade at substantial discounts to confirmed original examples.
The California dial, Roman numerals on the upper half and Arabic numerals on the lower half with a square marker at 6, appears on the 2940 both as original Rolex production and as later refinishing. Phillips Geneva Watch Auction TWO 2015 lot 277 is a documented original-production California 2940 example: stainless steel case, pink California dial, dated c.1941, estimated CHF 8,000–12,000 and sold at CHF 10,000 on the low estimate. Originality is difficult to establish because refinished California dials also circulate; the lot record should be checked against the individual dial.


'''Arabic radium dial.''' Arabic numeral hour markers with radium luminous fill, typically on a silvered or black base. The most commonly encountered 2940 dial configuration. Original radium fill has aged to a warm orange-brown patina on surviving examples; white or cream lume on a 2940 dial is almost always a refinish indicator.
Arabic-radium dials are documented on silvered and black bases, with hour markers filled with radium luminous compound. Original radium fill has aged to a warm orange-brown patina on surviving examples; white or cream lume on a 2940 dial needs inspection for refinishing or later replacement.


'''Two-tone contrasting zones.''' A c.1942 production variation dividing the dial into inner and outer zones with contrasting finishes — typically a silver outer zone with a darker inner track or vice versa. The two-tone layout was a Rolex dial design that traveled across several contemporaneous references and appears on the 2940 in examples dated to 1942 and the surrounding years.
Two-tone contrasting-zone dials divide the dial into inner and outer zones with contrasting finishes, typically a silver outer zone with a darker inner track or vice versa. The two-tone layout traveled across several contemporaneous references and appears on the 2940 in examples dated to 1942 and the surrounding years.


'''Salmon.''' A rare configuration. The Heritage Auctions “Two Tone Salmon Dial” example — a c.1942 2940 with a salmon-finish dial — is the best-documented example in the public auction record. Salmon dials on 2940 cases are scarce enough that any appearance at auction or dealer inventory draws collector attention disproportionate to the reference’s general market position.
Heritage Auctions catalogued a c.1942 two-tone salmon 2940. That lot documents the configuration; it does not establish production frequency or a general market premium.


'''Silvered and champagne.''' Silvered and champagne-finish dials with applied hour markers and a minute track represent the baseline dress-watch configuration for 2940s sold to retailers who did not specify a more unusual dial treatment. These are the most commonly surfaced dial type in dealer inventory.
Silvered and champagne-finish dials with applied hour markers and a minute track are also documented. Dealer listings are not a controlled measure of their share of production.


'''Black.''' Black lacquer or matte black dials appear on 2940 cases and run against the dominant dial language of the era. Original black-dial 2940s are scarce; the configuration is more commonly encountered as a refinish applied to a case whose original dial had degraded beyond reuse.
Black lacquer or matte black dials run against the dominant dial language of the era. Black-dial 2940s appear in the record, alongside refinished examples. Dial originality requires watch-specific inspection.


'''24-hour military.''' Very rare. A 24-hour dial layout — hour markers spanning 1 through 24 rather than 1 through 12 — surfaces on a small number of 2940 cases, typically in connection with military or specialized-use procurement. The configuration is the 2940’s most unusual dial variant and any example surfacing at auction commands a substantial premium over standard-dial prices.
A 24-hour dial with markers from 1 through 24 is reported on a small number of 2940 cases. The cited material does not establish its procurement history or a general price premium.


'''“Erbe Basel” dealer-signed.''' Dealer-signed dials surface on 2940s more frequently than on most later Rolex references, reflecting the 1940s practice of retailers commissioning co-signed dials for their own stock. The “Erbe Basel” signature — for the Erbe jewelry retailer in Basel, Switzerland — is one of the documented dealer signatures on 2940 dials.
Dealer-signed dials are documented on 2940 examples. The Erbe Basel signature is one recorded case; the cited sources do not establish how common retailer commissions were across the reference. The "Erbe Basel" signature, for the Erbe jewelry retailer in Basel, Switzerland, is one of the documented dealer signatures on 2940 dials.


<span id="hand-variants"></span>
<span id="hand-variants"></span>
=== Hand variants ===
===Hand variants===
 
Four hand styles are documented on surviving 2940s: Mercedes, sword, pencil, and dauphine. The hand set should be assessed with the dial, case, and movement.
Four hand configurations appear across the surviving 2940 corpus. Mercedes-style blued hands with luminous fill — the hour hand terminating in the circular Mercedes motif — surface on 1942 examples and predate the later standardization of Mercedes hands on the Submariner and Explorer lines. Sword luminous hands, broader and more tapered than the Mercedes style, appear on a range of 1940s 2940s. Pencil hands with radium fill are the most commonly encountered configuration and match the baseline Arabic radium dial layout. Dauphine hands — the faceted triangular hand shape more typical of dress watches — appear on silvered and champagne dial examples where the intent was a formal rather than sporting presentation.


Mismatched lume aging between dial markers and hands is the single most reliable indicator of hand replacement. On a 2940 whose dial lume has aged to orange-brown, hands with cleaner or differently-patinated lume suggest a service replacement; the two components should age in parallel if both are original.
Mismatched lume aging between dial markers and hands is one warning sign of a possible hand replacement. On a 2940 whose dial lume has aged to orange-brown, hands with cleaner or differently patinated lume need comparison with the dial, case history, and service record.


<span id="case-materials"></span>
<span id="case-materials"></span>
== Case materials ==
==Case materials==
 
Three case materials appear in the 2940 corpus.
Three case materials appear in the 2940 corpus.


'''Stainless steel''' is the most commonly encountered. The 2940 was Rolex’s workhorse steel Bubbleback of the wartime period, and steel examples constitute the bulk of the surviving population. The Phillips 2015 Lot 277 example is steel; so are the majority of dealer inventory listings across 1stDibs, Chrono24, and specialist vintage dealers.
Stainless-steel examples are documented in the Phillips lot and dealer records. Those listings do not establish the material proportions of the original production run.


'''14K gold-top over steel''' is the mid-tier configuration. A gold-top case carries a solid gold bezel and top-side of the mid-case with a steel caseback and internal structure — the gold appears on the visible surfaces without the cost of a fully solid gold case. 14K gold-top/steel 2940s sit in dealer inventory at a modest premium over comparable steel examples and were particularly common in the US and UK export markets.
14K gold-top over steel is the mid-tier configuration. A gold-top case carries a solid gold bezel and top-side of the mid-case with a steel caseback and internal structure. The gold appears on the visible surfaces without the cost of a fully solid gold case. 14K gold-top/steel examples are documented in dealer and auction records; the cited material does not establish a production share or universal price difference.


'''9K solid gold''' is the scarcest. The 9K gold configuration — permitted for hallmarking in the UK but not most continental European markets — was the British Commonwealth market option and carries British assay marks on the caseback and lugs. 9K gold 2940s appear less frequently than either steel or gold-top/steel examples and trade at a premium that reflects both their scarcity and their precious-metal positioning, though below the price a comparable 14K or 18K gold 3131 would command.
9K solid-gold examples are documented with British assay marks in the cited material. The available records do not establish their production share or a universal price relationship with steel or gold-top cases.


No 18K gold 2940 has surfaced in the indexed auction record. The absence is not conclusive — dealer and private records are not systematically indexed — but the 2940 appears to have been positioned as a steel, gold-top, and 9K gold reference rather than a premium solid gold one. The 3131 and its precious-metal siblings occupied that position in the catalog.
No 18K gold 2940 appears in the indexed auction record. That absence is not conclusive, and the available records do not define a complete material catalogue.


<span id="the-zell-bros-turtle-variant"></span>
<span id="the-zell-bros-turtle-variant"></span>
== The Zell Bros Turtle variant ==
==The Zell Bros Turtle variant==
The Zell Bros “Turtle Perpetual Timer” is a documented retailer-signed 2940 branch. The watch remains a 2940, with the name and dial signature recorded as part of the individual configuration.


The 2940 carries one documented retailer-specific variant that sits outside the standard dial catalog: the “Turtle Perpetual Timer” sold through Zell Bros, an Oregon-based jewelry retailer, with its own dial signature and a market-specific commercial name. The Turtle designation was Zell Bros’ retail branding rather than a Rolex designation, and the watches are standard 2940 cases with the Zell Bros dial treatment. The configuration is sufficiently documented that “Zell Bros Turtle” is a recognized 2940 sub-variant in the collector literature, and surviving examples trade at a premium over standard-dial 2940s reflecting both the retailer-signed dial and the named-variant collector interest.
The Turtle fits the broader record of retailer-signed Rolex dials in the mid-century US market. The cited sources do not establish how many such 2940s were made.
 
The Turtle example is one of several mid-century US retailer variants where a jewelry chain contracted with Rolex for signed-dial stock and gave the resulting watches retail-specific names. The practice was more common on 1940s and 1950s Rolex production than it is on any modern reference; the Zell Bros Turtle is the 2940’s best-known example.


<span id="auction-and-market-record"></span>
<span id="auction-and-market-record"></span>
== Auction and market record ==
==Auction and market record==
 
The public auction record cited on this page contains a Phillips California-dial lot and a Heritage salmon-dial lot.
Two public auction lots anchor the documented 2940 market picture, supplemented by dealer inventory data.


{| class="wikitable"
{| class="wikitable"
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|-
|-
| Heritage Auctions
| Heritage Auctions
| —
| n/a
| —
| n/a
| —
| n/a
| Two-tone salmon
| Two-tone salmon
| c.1942
| c.1942
| —
| n/a
|}
|}


The Phillips 2015 result is the headline data point. A steel 2940 with a pink California dial sold at CHF 10,000 on an estimate of CHF 8,000–12,000 — a market-range result for the configuration, with the California dial driving the estimate above what a standard Arabic-radium 2940 would command. The Heritage salmon-dial example is less completely documented in the public record but establishes the salmon dial as a documented configuration at auction-house level rather than a dealer-listing curiosity.
Phillips lot 277 was a steel 2940 with a pink California dial. It sold for CHF 10,000 against an estimate of CHF 8,000–12,000. The result belongs to that lot and configuration. Heritage’s salmon-dial lot documents that configuration at auction; its available record is less complete than the Phillips lot.


Dealer market data for the period 2020–2026 places the reference in a specific price band. Average private-sale pricing sits at roughly USD 2,352, with dealer pricing at an average of USD 3,455 — the dealer premium reflecting both retail margin and the dealer market’s tendency to carry better-condition or more complete examples. The broader price range runs from USD 2,860 at the bottom to USD 11,950 at the top, with the upper figure reflecting rare dial configurations (salmon, sector, 24-hour military), exceptional condition, or precious-metal cases. Five-year market change sits at roughly +36.2 percent, consistent with broader vintage Rolex appreciation over the same period but below the ten-year appreciation that a comparable Submariner or GMT-Master has delivered.
Dealer listings are not a controlled market series. They should be kept separate from the two cited auction lots when assessing an individual watch.


The 2940 sits in the accessible middle of the Bubbleback market. It is not as visually dramatic as the engine-turned 3372. It is not as historically pivotal as the 3131 or as rare as the 1858. It is not as metal-premium as a solid 18K gold 3131. What the 2940 offers is a wartime Rolex at a sub-USD-5,000 entry point in standard steel configuration, with clear paths to higher price tiers for better dials, better condition, and precious-metal cases. The market reflects that positioning.
The cited examples differ in case, movement and dial configuration. Auction results remain tied to each watch's condition, originality, metal and provenance.


<span id="serial-range-observations"></span>
<span id="serial-range-observations"></span>
=== Serial range observations ===
===Serial range observations===
 
The documented 2940 serial range runs roughly from the low 200,000s into the high 600,000s, which is enough to place examples into a wartime or late-run band even if it does not give exact factory dating.
The documented 2940 serial range runs from approximately 200,000 (c.1942) through approximately 690,000 (c.1949). The range is consistent with the 1940–1949 production window inferred from the surviving corpus, though the earliest serials in the low 200,000s suggest that production may not have begun in earnest until 1942 rather than 1940 — the first two years of the nominal window may have been a slow ramp-up or a production-overlap period with earlier references. The 1949 end of production coincides with the transition toward the references that would define the early 1950s Bubbleback era (4220, 4467, and the 4777/5015 pairings) as the two-piece case itself began to give way to the thinner Cal. 1030–powered watches.


<span id="collecting-considerations"></span>
<span id="collecting-considerations"></span>
== Collecting considerations ==
==Collecting considerations==
 
Dial configuration is a major part of assessing a 2940, but the cited lots do not support a general price range. Check the dial, lume, hands, case material and provenance together.
The 2940 is a reference where dial configuration drives value more decisively than case material or condition alone. A standard Arabic-radium steel 2940 in good unrestored condition trades in the low-to-mid four figures. A California-dial steel 2940, in comparable condition, trades at roughly double that. A salmon or sector dial example can push to the top of the reference’s documented range. A 24-hour military 2940 surfaces rarely enough that price discovery happens case by case. The dial catalog is the first item of diligence on any 2940 purchase.
 
Original-dial diligence is non-trivial. Refinished dials outnumber original dials in the surviving population — eight decades of service activity have given plenty of opportunity for radium replacement, re-lacquering, and full refinishes — and the refinishing industry in the mid-to-late twentieth century was proficient enough that a well-executed refinish can be difficult to detect. The indicators that matter: radium patina matching between dial and hands, printing sharpness consistent with 1940s-era dial manufacturing, correct font choices for the era (which refinishers often subtly miss), and the absence of refinisher signatures or marks on the dial back. Provenance documentation — auction-house lot photography, extract from Rolex archives for later references, retailer paperwork — helps but is rare for 2940s.
 
Hooded-lug skepticism is essential. Any 2940 offered with hooded lugs should be presumed an aftermarket modification until demonstrated otherwise, and the demonstration requires more than seller assertion. A seller who cannot produce either clear between-lug stamping showing the unchanged 2940 reference or professional authentication from a recognized vintage Rolex specialist has effectively not made the case. The reference’s authentic configuration is squared-off inner lugs; that is the baseline against which any deviation must be justified.
 
Case material verification matters at the high end of the market. 14K gold-top/steel and 9K solid gold examples carry substantially different value positions from steel 2940s, and hallmark photography is non-negotiable on any precious-metal listing. Cases that have been replated, regilded, or otherwise worked should be identified as such, and the premium a solid gold case commands should survive the verification step to be worth paying.


The 2940 trades primarily through specialist dealer inventory and the secondary auction market rather than at major Geneva houses. Phillips and Heritage have handled examples; Sotheby’s and Christie’s have occasionally included 2940s in mid-tier vintage lots; Antiquorum and Bonhams have listed them in catalog sales. The bulk of market activity, however, happens through vintage Rolex specialist dealers, forum-adjacent private sales, and platforms like Chrono24 and 1stDibs. Price discovery is accordingly uneven, and a given configuration can trade at widely varying prices depending on venue and market conditions.
Original-dial diligence on the 2940 is hard. Refinished dials are common, so radium matching, print quality, correct fonts, and any surviving provenance matter a lot more here than they do on easier later references.


<span id="still-open"></span>
A 2940 offered with hooded lugs needs clear between-lug 2940 stamping, case geometry and specialist authentication before its configuration is accepted. The documented standard configuration has squared-off inner lugs.
== Still open ==


Several questions about the 2940 remain unresolved in the current collector literature.
Case material verification matters at the high end of the market. 14K gold-top/steel and 9K solid gold examples carry substantially different value positions from steel 2940s, and hallmark photography is necessary when assessing a precious-metal listing. Cases that have been replated, regilded, or otherwise worked should be identified as such, and any value comparison should follow verification of the case material.


'''Total production.''' No public source documents 2940 production totals. The serial-range inference from ~200,000 to ~690,000 covers a ~490,000-unit span, but serial numbers in this period were not reference-specific — they covered the entire Rolex production of the year — so the actual 2940 share of that range is not documented.
The cited record is concentrated in specialist and auction listings. Results from different venues are not directly comparable, so each lot should be read with its condition and provenance details.


'''1940–1941 production.''' The earliest surfaced 2940 serials run in the low 200,000s, consistent with 1942 production. Whether any 2940s were produced before 1942 in non-trivial volume, or whether the reference was introduced on paper in 1940 but not pushed to volume production until 1942, is not documented.


'''Hooded-lug authenticity.''' The collector consensus is that hooded-lug 2940s are aftermarket modifications. A single rigorously authenticated hooded 2940 — with period-correct stamping, consistent lug geometry, and provenance from a dealer or auction house whose authentication standards are accepted in the specialist community — would revise this position. None has surfaced in the indexed record.
==Related references==
* [[Reference:3595|Bubbleback 3595]] (1941–1949)
* [[Reference:3065|Bubbleback 3065]] (1937–1950)
* [[Reference:2764|Bubbleback 2764]] (1937–1948)
* [[Reference:3131|Bubbleback 3131]] (1936–1948)
* [[Reference:4467|Bubbleback 4467]] (1945–1949)
* [[Reference:3458|Bubbleback 3458]] (1934–1948)


'''Caliber grade variation.''' Some 2940s are documented with 17-jewel movements, others with 18 jewels. Whether this reflects original production grade differences, service-era movement variants, or documentation inconsistency across sources is not established.
See also the [[Reference:bubbleback|Bubbleback family index]], [[Reference:Movements|movement reference]], [[Reference:Bracelets|bracelet & clasp guide]], and [[Reference:Serial-numbers|serial numbers by year]].


'''Dial configuration totals.''' The dial catalog (sector, California, Arabic radium, two-tone, salmon, black, 24-hour military, silvered, champagne, dealer-signed) is well-attested across surviving examples, but no public source documents relative production volumes. The rarity claims in the collector literature — “salmon is rare,” “24-hour military is very rare” — are inferred from auction and dealer frequency rather than documented against production records.
<gallery mode="packed" heights="180">
File:Ref 2940 hero.webp|1942 stainless-steel 2940
File:Ref 2940 full.webp|Rose-numeral dial example
File:Ref 2940 profile.webp|Bubbleback case profile
File:Ref 2940 dial-detail.webp|Center-seconds dial detail
</gallery>


== Sources ==
== Sources ==
* The Vintage Rolex Field Manual, Chevalier Edition — unknown, Morning Tundra
* ''The Vintage Rolex Field Manual'' — Colin A. White, Morning Tundra
* [https://www.phillips.com/auctions/watches Phillips — geneva two 2015 lot277]
* [https://www.phillips.com/detail/rolex/90975 Phillips Geneva Watch Auction TWO, lot 277, Rolex 2940 California dial] — Phillips
* [https://www.ha.com/ Heritage Auctions — 2940 salmon]
* [https://jewelry.ha.com/itm/timepieces/rolex-beautiful-two-tone-salmon-dial-bubbleback-ref-2940-stainless-steel-circa-1942/a/5422-54176.s Heritage Auctions, two-tone salmon dial Bubbleback ref. 2940, lot 54176]
* [https://www.bobswatches.com/rolex-blog/watch-review/rolex-bubble-back.html Bob's Watches — Rolex Bubble Back Collector's Guide] — Bob's Watches
* [https://www.bobswatches.com/rolex-blog/watch-review/rolex-bubble-back.html Bob's Watches — Rolex Bubble Back Collector's Guide] — Bob's Watches
* ''swisswatchexpo bubbleback''
* ''swisswatchexpo bubbleback''
* [https://www.watchuseek.com/ WatchUSeek — 2940 threads]
* WatchUSeek — 2940 discussion threads used as collector leads
* [https://www.tapatalk.com/groups/vintagerolexforum/ Vintage Rolex Forum — 2940 hooded debate]
* [https://www.tapatalk.com/groups/vintagerolexforum/ Vintage Rolex Forum — 2940 hooded debate]
* [https://www.1stdibs.com/ 1stDibs — 2940 listings]
* [https://www.1stdibs.com/ 1stDibs — 2940 listings]
* [https://www.rolexforums.com/ Rolex Forums — 2940]
* [https://www.rolexforums.com/~trfcom/showthread.php?t=372044 Rolex Forums, “Another Bubbleback question” — reference 2940 engraving discussion]
* [https://www.rolex.com/oyster-story/visionary-undertaking/at-one-with-movement Rolex Oyster Story: “At one with the movement”]; Rolex, 1931 Perpetual rotor history
* [https://calibercorner.com/ Caliber Corner — 630]
* [https://calibercorner.com/ Caliber Corner — 630]


[[Category:Bubbleback]]
[[Category:Bubbleback]]
[[Category:Working Draft]]

Latest revision as of 08:36, 29 September 2026


Bubbleback › 2940

1942 steel Bubbleback
1942 steel Bubbleback

The 2940 is a 31–32mm two-piece Bubbleback with center seconds. Published examples include stainless-steel, gold-top and 9K cases, with dial variants documented across 1940s auction and specialist records.

Core facts

detail value
reference 2940
family Bubbleback (collector name; never official Rolex usage)
production c.1940–1949; many cited examples date to 1942–1947
case diameter 31–32mm
case shape round
case construction two-piece (caseback screws directly into case middle)
lug-to-lug ~38–38.5mm
lug width 16–17mm
lugs squared-off inner profile (hooded examples debated)
bezel smooth, polished, domed
crystal acrylic
seconds center sweep (not sub-seconds)
movement Cal. 9¾′′′, 17 jewels (some 18j); some examples Cal. 630
case materials stainless steel, 14K gold-top/steel, 9K solid gold
serial range ~200,000 (c.1942) to ~690,000 (c.1949)

Where it sits in the line

The 2940 is a center-seconds Bubbleback that followed the two-piece case introduced by the 3131 and 3132. Its center-mounted seconds hand runs from the 9¾′′′ movement family rather than a subsidiary register at 6. Published records place production roughly from 1940 through 1949, with many cited examples dated 1942–1947.

2940 rose-numeral dial Phillips lot
Phillips Geneva 2015 lot, rose-numeral dial

Within the Bubbleback range, the 2940 sits beside the sub-seconds 2764, the more mixed-metal 3065, and the engine-turned 3372. Steel, gold-top over steel, and 9K solid-gold cases are documented; the cited records do not establish production proportions. The documented serial range runs from the low 200,000s to the high 600,000s, which fits roughly 1942 to 1949. Unlike later sports references, the 2940 does not break into neat generations. The variation is in dials, hands, and case metal.

The wartime commercial position

The early 1940s records show the 2940 in more than one market. Dial and case combinations vary across the surviving examples, but the cited sources do not establish how Rolex allocated production by market.

The two-piece case

The 2940 uses the two-piece case architecture the 3131 introduced in 1936: a round mid-case with the bezel integral to the case middle, closed at the back by a screw-down caseback that threads directly into the case. The case has no separate bezel ring or discrete movement-holder. It measures 31–32mm in diameter with a lug-to-lug of roughly 38–38.5mm and a lug width between 16 and 17mm. The bezel is smooth and domed, polished, unmarked, set slightly proud of the crystal aperture.

The inner lug profile is squared-off. This is the standard 2940 lug configuration, and it is the reference point for checking a hooded-lug claim.

2940 Bubbleback profile bulge
1946 example, profile shows Bubbleback caseback bulge

The hooded-lug debate

Published Bubbleback references associate the hooded-lug case form with the 3065 rather than the 2940. A 2940 offered with hooded lugs therefore needs close comparison of caseback stamping, lug geometry and provenance before the reference is accepted.

A hooded-lug 2940 claim needs positive evidence. The cited collector record does not establish a confirmed original 2940 with that case form.

Serial and reference engraving

2940 cases carry the reference number engraved between the upper lugs and the serial number engraved between the lower lugs, consistent with the 1920s–1940s Oyster convention. Caseback interiors carry the Oyster Watch Co. signature along with period-correct patent and hallmark markings. The reference is also repeated on the caseback interior. This double-engraving of the reference makes 2940 authentication relatively straightforward where the lugs have not been altered; forged-hood examples can be detected by comparing the between-lug engraving (still typically legible as 2940) against the lug profile (incorrectly modified to a hooded form).

The movement

The 2940 runs on Rolex's 9 3/4 ligne automatic family, usually 17 jewels and sometimes 18 in better-grade or later-service examples. The practical point is simple: this is a Bubbleback-era automatic with center sweep seconds, not a special one-off movement.

The cited 2940 movements do not have a documented hacking feature. Pulling the crown stops the hands while the seconds continue to run, so exact synchronization requires a small setting correction.

Cal. 630 is cited on some 2940 examples as the numbered designation for the 9¾′′′ sweep-seconds configuration. Other catalogues give only the ligne measurement. The movement and its markings should be inspected on each watch rather than inferred from the reference alone.

Dial variants

The 2940 has a broad documented dial range. Some of this breadth reflects Rolex's pre-war practice of configuring dials to retailer specification; some of it reflects the reference's long production run across multiple export markets; some of it reflects refinishing activity over the subsequent eight decades.

2940 dial close-up rose numerals sub-seconds
Applied rose numerals + sub-seconds register

The sector dial, multi-tone silver with dot and Arabic indices divided into concentric or radial zones, appears less often in the cited 2940 record. The sector layout appears on some 2940 cases; the cited auction record does not establish a general price premium.

The California dial, Roman numerals on the upper half and Arabic numerals on the lower half with a square marker at 6, appears on the 2940 both as original Rolex production and as later refinishing. Phillips Geneva Watch Auction TWO 2015 lot 277 is a documented original-production California 2940 example: stainless steel case, pink California dial, dated c.1941, estimated CHF 8,000–12,000 and sold at CHF 10,000 on the low estimate. Originality is difficult to establish because refinished California dials also circulate; the lot record should be checked against the individual dial.

Arabic-radium dials are documented on silvered and black bases, with hour markers filled with radium luminous compound. Original radium fill has aged to a warm orange-brown patina on surviving examples; white or cream lume on a 2940 dial needs inspection for refinishing or later replacement.

Two-tone contrasting-zone dials divide the dial into inner and outer zones with contrasting finishes, typically a silver outer zone with a darker inner track or vice versa. The two-tone layout traveled across several contemporaneous references and appears on the 2940 in examples dated to 1942 and the surrounding years.

Heritage Auctions catalogued a c.1942 two-tone salmon 2940. That lot documents the configuration; it does not establish production frequency or a general market premium.

Silvered and champagne-finish dials with applied hour markers and a minute track are also documented. Dealer listings are not a controlled measure of their share of production.

Black lacquer or matte black dials run against the dominant dial language of the era. Black-dial 2940s appear in the record, alongside refinished examples. Dial originality requires watch-specific inspection.

A 24-hour dial with markers from 1 through 24 is reported on a small number of 2940 cases. The cited material does not establish its procurement history or a general price premium.

Dealer-signed dials are documented on 2940 examples. The Erbe Basel signature is one recorded case; the cited sources do not establish how common retailer commissions were across the reference. The "Erbe Basel" signature, for the Erbe jewelry retailer in Basel, Switzerland, is one of the documented dealer signatures on 2940 dials.

Hand variants

Four hand styles are documented on surviving 2940s: Mercedes, sword, pencil, and dauphine. The hand set should be assessed with the dial, case, and movement.

Mismatched lume aging between dial markers and hands is one warning sign of a possible hand replacement. On a 2940 whose dial lume has aged to orange-brown, hands with cleaner or differently patinated lume need comparison with the dial, case history, and service record.

Case materials

Three case materials appear in the 2940 corpus.

Stainless-steel examples are documented in the Phillips lot and dealer records. Those listings do not establish the material proportions of the original production run.

14K gold-top over steel is the mid-tier configuration. A gold-top case carries a solid gold bezel and top-side of the mid-case with a steel caseback and internal structure. The gold appears on the visible surfaces without the cost of a fully solid gold case. 14K gold-top/steel examples are documented in dealer and auction records; the cited material does not establish a production share or universal price difference.

9K solid-gold examples are documented with British assay marks in the cited material. The available records do not establish their production share or a universal price relationship with steel or gold-top cases.

No 18K gold 2940 appears in the indexed auction record. That absence is not conclusive, and the available records do not define a complete material catalogue.

The Zell Bros Turtle variant

The Zell Bros “Turtle Perpetual Timer” is a documented retailer-signed 2940 branch. The watch remains a 2940, with the name and dial signature recorded as part of the individual configuration.

The Turtle fits the broader record of retailer-signed Rolex dials in the mid-century US market. The cited sources do not establish how many such 2940s were made.

Auction and market record

The public auction record cited on this page contains a Phillips California-dial lot and a Heritage salmon-dial lot.

Venue Date Lot Material Dial Notes Result
Phillips Geneva Watch Auction TWO 2015-05-09 277 SS Pink California c.1941 CHF 10,000 (est CHF 8,000–12,000)
Heritage Auctions n/a n/a n/a Two-tone salmon c.1942 n/a

Phillips lot 277 was a steel 2940 with a pink California dial. It sold for CHF 10,000 against an estimate of CHF 8,000–12,000. The result belongs to that lot and configuration. Heritage’s salmon-dial lot documents that configuration at auction; its available record is less complete than the Phillips lot.

Dealer listings are not a controlled market series. They should be kept separate from the two cited auction lots when assessing an individual watch.

The cited examples differ in case, movement and dial configuration. Auction results remain tied to each watch's condition, originality, metal and provenance.

Serial range observations

The documented 2940 serial range runs roughly from the low 200,000s into the high 600,000s, which is enough to place examples into a wartime or late-run band even if it does not give exact factory dating.

Collecting considerations

Dial configuration is a major part of assessing a 2940, but the cited lots do not support a general price range. Check the dial, lume, hands, case material and provenance together.

Original-dial diligence on the 2940 is hard. Refinished dials are common, so radium matching, print quality, correct fonts, and any surviving provenance matter a lot more here than they do on easier later references.

A 2940 offered with hooded lugs needs clear between-lug 2940 stamping, case geometry and specialist authentication before its configuration is accepted. The documented standard configuration has squared-off inner lugs.

Case material verification matters at the high end of the market. 14K gold-top/steel and 9K solid gold examples carry substantially different value positions from steel 2940s, and hallmark photography is necessary when assessing a precious-metal listing. Cases that have been replated, regilded, or otherwise worked should be identified as such, and any value comparison should follow verification of the case material.

The cited record is concentrated in specialist and auction listings. Results from different venues are not directly comparable, so each lot should be read with its condition and provenance details.


Related references

See also the Bubbleback family index, movement reference, bracelet & clasp guide, and serial numbers by year.

  • 1942 stainless-steel 2940
    1942 stainless-steel 2940
  • Rose-numeral dial example
    Rose-numeral dial example
  • Bubbleback case profile
    Bubbleback case profile
  • Center-seconds dial detail
    Center-seconds dial detail

Sources

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