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Blog: Rolex Oyster case

Date: 24 February 2015

Copyright © David Boettcher 2006 - 2019 all rights reserved.

I make additions and corrections to this web site frequently, but because they are buried somewhere on one of the pages the changes are not very noticeable, so I decided to create this blog section to highlight new material. Here below you will find part of one of the pages that I have either changed or added to significantly.

The section reproduced here is from my page about Rolex.

If you have any questions or comments, please don't hesitate to contact me via my Contact Me page.

The Waterproof Oyster Case

1929 Oyster Case Back
1929 Oyster Case Back
Image by permission ©

For the Rolex Oyster a new waterproof case was designed and patented. If you look in the case back of an early Rolex Oyster such as the one pictured here you will see four patents listed: two "Great Britain Patents" 260554/1925 and 274789, and below them two "Swiss Patents" 114948 and 120851. These are a British and a Swiss patent for each of two inventions. The first British / Swiss pair (260554 / 114948) were for the waterproof screw down crown; the second pair (274789 / 120851) were for the waterproof Oyster case.

An interesting feature of the patent for the case is that it begins by saying that the invention refers to a shaped or "forme" watch case (i.e., different from the usual round or circular form). The patent goes on to illustrate and describe an octagonal case and the means by which this case can be made watertight.

Referring to the cross section below, the movement is held in an externally threaded carrier ring 5, which passes through the centre of the shaped case. The front bezel and case back, both numbered 11 in the drawing, screw onto the external threads of this carrier ring, rotating in opposite directions and clamping the middle part of the case between them to form the water tight seal.

Oyster case cross section
Oyster case cross section

The design of the threaded carrier ring is so reminiscent of the screw cases designed by François Borgel that it is not surprising that many people think the Borgel company, then owned by the Taubert family, must have been involved in the design, but no link has yet been proven. In their book on Rolex, Dowling and Hess note that Rolex produced a small series of watches using the original one-piece Borgel screw case in 1922. In fact, the relationship between Borgel and Rolex goes back to way before the 1922 date mentioned by Dowling and Hess. The image here shows a Borgel case with London import hallmarks for 1910 and the W&D sponsor's mark entered by Wilsdorf and Davis.

Borgel case back
Borgel case with London hallmarks for 1910 and W&D mark

The Borgel company also supplied Rolex with three piece 1903 Borgel patent screw cases in the 1920s. The Oyster case was virtually identical to the earlier Borgel design and it seems obvious that the Oyster case was based on the 1903 Borgel design. The question is, why weren't the Oyster cases made by the Borgel company, then in the ownership of the Taubert family?

Wilsdorf was working on the Rolex Oyster in the years before it was revealed in 1926, and the Borgel company was taken over by the Taubert family in 1924, so perhaps Wilsdorf didn't want to approach what was essentially a new and untested company. The Tauberts would most likely have insisted on the Borgel trademark of the initials FB over a Geneva key to appear on any cases they made, which wouldn't have suited Wilsdorf.

The threaded Oyster case backs were milled with small radial grooves like the edge of a coin to provide the grip needed to tighten and release them by hand, the same as François Borgel had been using on the bezels of his screw cases since 1891. To get a tighter seal than possible by hand tightening in 1926 Wilsdorf designed a tool that engaged with the millings and enabled greater torque to be applied than by hand. On 3 October 1929 Wilsdorf applied for a patent for this tool, which was published on 16 January 1931 under N° CH 143449. The millings on the case backs of modern Rolex watches, and the case openers used today, derive from these early designs.

Oyster cases accumulated a series of patent numbers inside their backs over the years, including D.R.P. 471002, a German "Deutches Reich Patent" for "Staub und wasserdichtes Uhrgehaeuse" (dust and waterproof watchcase) granted on 2 February 1929.

Who Made the First Rolex Oyster Cases?

Glasgow 1927 to 1928 RWCLtd
RWCLtd, hallmarks Glasgow 1927/28
PdM No. 1 with number 136

Rolex do not reveal information such as the identity of the case maker who supplied the cases for the first Rolex Oysters. However, beginning in the mid 1920s Swiss watch cases of gold and platinum had to be marked to identify the case maker. These marks, called Poinçons de Maître, were very small, and the identity of the maker was encoded, so they are not well known. I am not going to go into this in detail here, you can find more about it on my page about Swiss Poinçons de Maître, but the important point is that these marks can in principle be read to identify the maker of a watch case. The problem is that they are so small they usually can't be read from photographs, at least not at the resolution commonly published on the internet.

Thanks to Crispin at I was able to examine nine high resolution pictures of early Oyster cases. From these I was able to date the cases from the date letter of the British import hallmarks, all impressed by the Glasgow Assay Office, and to read the symbols and numbers of the Poinçons de Maître (PdM). Since then I have also seen a case with Glasgow Assay Office import hallmarks and the date letter "d" for the year 1926 to 1927. All the cases bore the sponsor's mark of "R.W.C.Ltd" inside an oval shield, both the letters and shield being incuse, that is impressed into the plate rather than being in relief or cameo.

The image shows a typical Glasgow Assay Office import hallmark for 1927 to 1928. Reading from the top there is the sponsor's mark R.W.C.Ltd which shows who or what company submitted the item for hallmarking, then below that the sideways "9" and ".375" standard mark for nine carat gold, Glasgow Assay Office town mark for imports of two prone and opposed "F"s and finally the date letter "e" for 1927 to 1928. The Glasgow date letter was changed on 1 July each year, so each letter represents parts of two calendar years. There is more about this type of mark on my page at British import hallmarks.

Oyster case hallmarks
All hallmarks Glasgow Assay Office
transfer of patent 114948
Transfer of patent 114948

The hallmarks cover a ten year period from July 1926 to June 1937 and all the cases, except the last, have the Poinçon de Maître of a hammer head bearing the number 136. This shows that they were made by the company of C. R. Spillmann SA of La Chaux de Fonds, later Chêne-Bourg and this shows that C. R. Spillmann SA were the makers of the first Rolex Oyster cases.

The company C.R. Spillmann was involved in the acquisition by Wilsdorf and Rolex of the rights to the Perregaux and Perret patent for the screw crown, CH 114948.

The record from La Fédération Horlogère Suisse shown here records the transfer in October 1925 of the rights to the Perregaux and Perret patent CH 114948, first to C.R. Spillmann et Cie,, and then onwards from Spillmann to Hans Wilsdorf. Together with the Poinçons de Maître from the Oyster cases dating back to 1927 this shows that the Spillmann company not only made the waterproof cases of the first Rolex Oysters but was heavily involved in the design of, and in fact probably were the actual designers of, the waterproof case.

PdM No.2 with number 136

The mark of a hammer with handle and the number 136 shown here is in the case of a Rolex Oyster with Glasgow Assay Office import hallmarks for nine carat gold and the date letter "d" for 1926/27. Although the registrant of the hammer with handle number 136 is not in the 1934 list I think it is safe to say that it must have been C.R. Spillmann SA.

In later years C. R. Spillmann specialised in chronographs and made all of the early Omega Speedmasters and most of the Rolex Daytona cases until Rolex brought production in house. Thanks to James Dowling for this information.

The company of C.R. Spillmann SA were listed as makers of gold watch case in La Chaux de Fonds. An obituary in La Fédération Horlogère Suisse recorded that Charles-Rodolphe Spillmann died on September 7th 1938. He was the founder and managing director of the company. He was also a founder and member of the executive committee of the Society of Swiss watch case manufacturers. The address given in Spillmann's obituary was La Chaux-de-Fonds, but the 1934 list of PdM gives the company address as Chêne-Bourg. I think that the company of C.R. Spillmann had its headquarters in La Chaux-de-Fonds, the building is still there listed as a Swiss heritage site of national significance, and a factory in Chêne-Bourg.

The CR Spillmann SA Poinçon de Maître was cancelled on 5/4/1988. I am not sure whether the company was dissolved or taken over.

If you have any questions or comments, please don't hesitate to contact me via my Contact Me page. Back to the top of the page.

Copyright © David Boettcher 2006 - 2019 all rights reserved. This page updated June 2018. W3CMVS.