Rolex. A Stainless Steel Chronograph Wristwatch with Bracelet and Black "Sigma" Dial

The present reference 6263 features a dial that is known as a "Sigma" dial, indicated by two small Sigma symbols on either side of the "T Swiss T". The Sigma symbols indicate that the baton numerals and hands on a dial are made of gold, in this case white gold. Sigma dials were first seen on the reference 6240, and were nicknamed "Goute A Prior" by Italian collectors and originally referred to the union of three Rolex dial producers: Singer, Stern, and Beyeler. On later references, the Sigma came to refer to indices and hands in gold. This example is known as a "Tight Sigma" where the sigma signs are closer together and less common.

For a note on the "Goute A Prior", see Rolex Daytona, a legend is born by Carlo Pergola, Stefano Mazzariol, & Giovanni Doss, p. 82. An example of a reference 6263 with Sigma Dial is illustrated on p. 136.