In 1963, Rolex introduced the reference 6239, the very first model of the iconic Cosmograph and they moved the tachymetre scale from the dial to the bezel. The present watch is from the very first year and has many attributes that make it highly collectible today.

First, it is fitted with the highly coveted 'Double Swiss' dial and the case back is stamped 6238. Rolex used dial stamps made from previous chronograph models when it began the production of the Daytona, they also used case backs already made and in stock for the previous chronograph reference 6238 and used them for the early Cosmographs under 1 million serial number. Secondly, the present watch is fitted with the MK1 bezel that is recognised by the 275 intermediate unit and the small hash marks found entirely on the bezel. Thirdly, the subsidiary registers have turned a wonderful deep brown and they have aged uniformly together, which gives a very appealing and a nice contrast to the silvered dial. Finally, the watch still retains its hand written Guarantee dated 1966 rendering this an important Cosmograph from the first year of production.