Accompanied by a letter from Mr. Marco Richon, Musée Omega, confirming that the present watch was made as a prototype of an Omega Automatic Seamaster "Ploprof" diver's wristwatch in the early 1970s. It is part of a small series of less than 12 examples produced with a titanium case made by the casemakers Schmitz Frères of Granges.
In the 1970s, Omega was running a series of tests with titanium cases. The aim was to reduce the weight of the rather large and massive "Ploprof" watches as much as possible by using titanium which is not only 40 less heavy than steel but also more resistant to corrosion. The project was finally abandoned due to the extremely expensive cost of this material.
The movement no. 31'508'923 was finished on 7 December 1971 and sold with a stainless steel case in April 1972. According to Mr. Richon, the case was exchanged to a later date in the context of a standard exchange.
The Seamaster 600 Professional model, also called "PLOPROF" for PLOngeur PROFessional, professional diver, was launched in 1970. It took over 4 years of study and research to design this watch. The monocoque case of the present watch is made out of one piece of titanium, the examples produced in series were cased in massive steel.
Commander Jacques Cousteau used a "PloProf" during a series of experiments at depths of around 500 metres.
The "PloProf" is described and illustrated in Omega Saga by Marco Richon, pp. 136 & 137.