SIGNED ROLEX, SUMBARINER, RED DEPTH MODEL, REF. 6536, CASE NO. 112’122, CIRCA 1955

Reference 6536/1, successor of reference 6536, was introduced in 1955 and remained in production until 1959. Essentially identical to its predecessor it was also available with the chronometer version of calibre 1030, featuring a 6 mm. crown with Brevet cross to the top and no guard to protect it.

This particular example is exceptionally rare due to its red depth printing, which usually only appears on reference 6536 but also appears in the earliest references 6536/1, such as this one as indicated by the stamp inside the case back showing production in the fourth quarter of 1955. It can safely be assumed that Rolex tested a rating indication in red without mentioning feet or meters before finally settling on the white "100m=330ft" found on later models.