The reference 6240, introduced in the mid-1960s, was the very first Rolex Cosmograph to feature screw-down chronograph pushers and a Triplock crown, marking the evolution from the earlier pump-pusher models to the fully waterproof Oyster Cosmograph. Produced in limited numbers, the 6240 remains one of the rarest and most sought-after early Daytona references.

The present example is distinguished by its later “Sigma” black dial, identified by the small sigma symbols flanking the “T SWISS T” signature at 6 o’clock, denoting the use of solid gold hour markers and hands. The glossy black surface with contrasting silver registers creates superb visual balance and depth.

The watch retains its original Mark I black acrylic bezel, the earliest type fitted to this reference, characterized by its distinct thin font and period-correct tachymeter scale, a highly collectible feature among connoisseurs. Together with its millerighe pushers and Jubilee bracelet, it embodies the quintessential early screw-down Daytona aesthetic.

A superb and historically significant Rolex Cosmograph Daytona reference 6240, combining the technical innovations of the first Oyster-cased chronograph with rare early components and timeless elegance, a true highlight for the discerning Rolex collector.