Part of the fun of getting into the vintage Rolex gathering game is finding all the different plan subtleties. What’s more, a considerable lot of these subtleties can be found on the watch dials. Today we investigate the birthplaces of the Rolex Sigma dial and what that can mean for the estimation of a vintage Rolex watch.
The Sigma Symbol and APRIOR
In the 1970s, a gathering of Swiss watchmakers who were important for the L’Association pour la Promotion Industrielle de l’Or or APIOR (which translates to The Association for the Industrial Promotion of Gold) shaped an authority initiative to feature the utilization of gold on watches.
Similar to how the “Chronometer” designation was controlled and ensured by Contrôle Officiel Suisse des Chronomètres (COSC) to signify ideal timekeeping exactness, APRIOR needed to formalize how watchmakers meant the utilization of valuable gold in watches – particularly significant on steel watches since tempered steel and white gold are comparative in color.
The image picked was the Greek letter Sigma: σ. As per a US Patent Office Registration Certificate (recorded in August 1971 and enlisted in July 1972) the σ mark “affirms that the products are of Swiss birthplace and contain strong gold up to a specific norm as set up by the Swiss statutory prerequisites concerning the control of the utilization of gold and fulfill guidelines and quality set up by the candidate.” It likewise specifies that the imprint was “First utilized February 25, 1970; in commerce approximately Mar. 1, 1970.”
The Sigma imprint could be utilized on the dial, wristband, or caseback of watches to imply the presence of gold. Some celebrated watch marks that utilized the APRIOR Sigma mark included Patek Philippe, Vacheron Constantin, IWC, and obviously, Rolex .
Rolex and the Sigma Dial
Sigma dials can be found on Rolex watches dating from the mid 1970s until the latter piece of the decade; anyway they can now and then be found on Rolex watches from the late 1960s, as the “Sigma” image was being utilized by certain dial makers before it turned out to be formally received in the mid 1970s . Rolex Sigma dials have two σ marks encompassing the “T SWISS T” signature just shy of 6 o’clock marker on the dial (“T” alludes to the utilization of tritium as glow on the dial). In this manner, Rolex Sigma dials indicate that the hand-applied lists and hands are make from 18k gold.
Rolex Sigma dials are all the more frequently found on tempered steel models (as an approach to differentiate between the steel case and arm band and white gold subtleties on the dial); anyway there are likewise instances of the Sigma dial on two-tone and yellow gold Rolex models.
We have seen Rolex Sigma dials on vintage Daytona, Date, Datejust, Day-Date, and Cellini watches. You won’t discover Sigma dials on models like the Submariner, Sea-Dweller, or Explorer from a similar period since Rolex didn’t have gold encompasses around the painted tritium hour markers at that time.
Since Rolex just utilized the Sigma dial for a modest bunch of years during the 1970s, it comes as nothing unexpected that the little σ markings can add to the estimation of a vintage Rolex watches. Today, vintage Rolex Daytona chronographs with Sigma dials are especially collectible, and run an exceptional when they surface at auction.