Omega
Seamaster 300 COSC - Pro Diver Helium valve

Diving watch Omega vintage Seamaster 300 Helium Valve from 1995. A collectible pre-owned watch, instantly recognizable by its blue color and helium valve positioned at 10 o’clock on the case. Certified chronometer by the C.O.S.C. in Geneva, it marked Omega’s strong return to the professional diving watch market.

A story that began in 1948 with a prototype developed by Omega at the request of the post-war British Royal Navy. This prototype, predating both the Blancpain Fifty Fathoms and the Rolex Submariner, introduced an O-ring seal that replaced traditional rubber gaskets for improved resistance to moisture, pressure, and temperature changes. In 1955, diver Gordon McLean set a depth record in Australia at 62.5 meters wearing a Seamaster. Later, in the 1960s, the Seamaster 600 Proplof would equip Comex divers and the legendary Jacques Cousteau’s team.

The model shown here is from the first series of Seamaster 300 watches from 1995, featuring the Omega 1120 movement—an automatic 23-jewel caliber based on the ETA 2892-A2 (21 jewels). Omega modified this ETA base to achieve chronometer-grade performance for its 1120 caliber. It features a Glucydur balance wheel with bi-directional winding, Stop-Seconds function, quick-set date adjustment, and a 44-hour power reserve when fully wound. The movement runs at 28,800 vibrations per hour and includes a Nivarox hairspring regulated via an Etachron regulator.

This is the very model chosen by Jean-Claude Biver, head of Omega in 2002, to reach an agreement with the James Bond 007 franchise. It was selected to replace the Rolex Submariners worn by Roger Moore in previous films and appeared on the wrist of Pierce Brosnan in *GoldenEye*. A special edition of the Seamaster 300 ref 2537.80 stamped with the 007 logo was produced in 2002 to commemorate this collaboration.

You can find more insights and anecdotes about watch manufacturers and their most iconic models in our "Mostra Mag" — the blog of Mostra Store, boutique in Aix-en-Provence.

Discover our pre-owned Omega Seamaster