MK Personal Collection Rare Rolex Steel Cosmograph Sigma Dial Wristwatch Ref 6263 Circa 1974

MK Personal Collection The present lot is part of a larger privately held collection and is intended for exhibition purposes only. Rare Rolex Steel Cosmograph Sigma Dial Wristwatch Ref 6263 Circa 1974. This fine men's steel Rolex Daytona Cosmograph with three-body construction case and screwed-down case back, buttons and crown Serial # 4,139,403 that measures 44.00mm x 41.00mm including the crown. The watch has a tachometer graduation on the steel bezel to 200 units per hour, bi-colored original black and silver with applied steel bâton indexes, luminous dots, outer minute/seconds track and subsidiary dials for the seconds, the 12-hour and 30-minute registers with luminous steel "bâton" hands, Rolex Cal. 727 rhodium plated 17 jewel movement with straight line lever escapement, monometallic balance adjusted to 3 positions, shock-absorber, self-compensating Breguet balance spring, microstella regulating screws. The dial, case and movement are all signed. Reference 6263 was in production - together with its metal-bezel sibling reference 6265 - since the late 1960s until 1987. The final evolution of the manual Daytona line, it is considered by many the most representative and iconic reference of the line, incorporating all the details which made the Daytona a masterpiece of design: bezel with black insert bearing a tachymetre scale, screw-down pushers, and the unmistakable Rolex Oyster case. The present version with silver dial and black sub-dials/registers has a stealth and sporty feel but also grants the timepiece an undeniably enormous aesthetic impact thanks to the black/white chromatic scheme which alternates obviously on the dial. The present example manufactured circa 1974 is a variant from the norm as it features an elegant and attractive "Sigma’" dial. The "T Swiss T" signature at 6 o'clock is flanked by the Greek symbol Sigma, denoting the markers are white gold. Research shows that the "Sigma" notation appeared on Rolex dials in the early 1970s, following the issue of a set of guidelines by APRIOR (Association pour la promotion industrielle de l’or: Association for the industrial promotion of gold). Such guidelines indeed suggested (but it was not compulsory, hence not all dials with gold bear the sigma) to add the Greek letter sigma to the dial of watches bearing gold details (such as the markers, in this case). Possibly due to the very cryptic nature of this designation, it was abandoned after a few years.