The helium valve, allowing helium and other gases to escape hence enabling the watch to withstand compression even at extreme depths, was developed by Rolex in cooperation with the French diving firm COMEX and used for the Submariner references 5513 and 5514 (see lots 160 and 334 in this auction). Following the success of these models, Rolex decided to commercialize their invention with the launch of the celebrated Sea-Dweller reference 1665 in 1967, the first wristwatch designed for use in saturation diving, fitted with a Rolex patent valve in the band and guaranteed waterproof to 610 meters depth.
The model was rushed to production while Rolex had not received the final approval for the patent of the helium valve, resulting in the very first models of reference 1665 being sold with the case backs engraved (Patent Pending) in parenthesis. According to literature, only around 150 examples of these early examples were made with serial numbers ranging between 1.7 million and 2.2 million.
The present reference 1665 is one of these extremely rare examples, featuring a number of specific characteristics of this celebrated version, clearly distinguishing them from their "patented" successors: - most remarkably the so-called Mark I or Mk I dial, standing out by the colour of the double red printing of the "Sea-Dweller" on the first line followed by the "Submariner 2000" on the second line. The initial red print, possibly printed over white paint, has over time faded to a pink, almost white colour. The two lines are of identical size. Furthermore the letter "B" of the word SUBMARINER is perfectly aligned with "S" of the model name SEA-DWELLER
- "Oyster Gas Escape Valve" and (Patent Pending) engraved around the case back
- inside of the case back featuring reference 1665, the last three digits of the serial number and quarter and year of production
Furthermore preserved in overall appealing condition, the present Patent Pending Double Red Sea-Dweller must be considered a highlight for the collector of this exceedingly rare model.
Reference 1665 "Patent Pending" is described and illustrated in Rolex Submariner Story by Franca e Guido Mondani, Lele Ravagnani, Guido Mondani Editore, pp. 160 & 161, and illustrated in 100 Superlative Rolex Watches by John Goldberger, p. 190.