ROLEX - a gentleman's Oyster Perpetual Submariner bracelet watch with helium escape valve. Issued by Comex. Circa 1972. Reference 5513, serial 3530753. Signed automatic calibre 1520. Black dial with luminous hour markers, date aperture to three. Calibrated bezel, stainless steel case fitted to a stainless steel Oyster bracelet with Fliplock clasp. 39mm.

From the front this watch appears to be a standard Rolex 5513 Submariner but a glance at the case edge at the 9 o'clock position reveals something unusual. The small steel disc or button signifies that this watch is something very special and continuing to turn the watch over with show the famous appellation 'COMEX' on the case back.

The watch dates from 1972 and illustrates the symbiotic relationship between the two companies. Rolex were developing the helium escape valve that would allow watches to be used at depths that demanded saturation diving and COMEX provided a test bed for these watches which they needed to work safely at such depths.

The earliest COMEX watches did not always have the company logo on the dial but did on the case back. This early example provides a fascinating insight into the progression from Submariner to Sea-dweller with the help of this pioneering team of engineers.