Reference:Movements: Difference between revisions

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” ([https://myretrowatches.co.uk/wp-content/uploads/2024/09/Valjoux-VZ-23-Technical-Guide.pdf 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.

| 13 lignes and 17 jewels in the Antiquorum Nutting record; Sotheby’s records 17 jewels for case 372822

| [[Reference:3525|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 [[Reference:pre-daytona-chronographs|pre-Daytona chronograph guide]].

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.

| Prince Brancard ref. 1855, serial 143**, circa 1930

| 8-position adjustment, against the more typical 6

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.

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 [[Reference:1500|ref. 1500]] as a Date fitment in its Cal. 1575 table ([https://irp-cdn.multiscreensite.com/0b5fdf83/files/uploaded/1.0%20RolexBook-23Mar.pdf The Vintage Rolex Field Manual, caliber table]); a [https://www.clubderelojeria.com/comunicaciones/R/ROLEX/rolex1575/ROLEX%201575.pdf 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. [https://www.bobswatches.com/rolex-blog/watch-review/vintage-week-rolex-oyster-perpetual-chronometer-date-ref-1500.html 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.