Rolex Sea-Dweller 16660

A transitional reference that propelled Rolex’s saturation diving watch into the modern era, the Sea-Dweller 16660, affectionately nicknamed the “Triple Six,” was in production from approximately 1978 to 1989.¹ It stands as a pivotal model in the Sea-Dweller’s lineage, bridging the gap between the vintage acrylic crystal models and the modern, more robust tool watches that followed.² Its significance lies in the major technical upgrades it introduced, most notably the shift from a plexiglass crystal to a scratch-resistant sapphire crystal and a significant increase in its depth rating to 4,000 feet (1,220 meters), doubling that of its predecessor.³

The “Triple Six” is a fascinating reference for collectors due to its relatively short production run and the variations that exist within it. Early models retained a matte dial similar to the previous Reference 1665, while later examples featured a glossy dial with applied white gold hour markers, a hallmark of modern Rolex sports models.⁴ This evolution in dial production, coupled with variations in caseback engravings and the existence of ultra-rare COMEX-signed versions, makes the 16660 a rich area for study and collection.

Variations

The most significant variations within the Reference 16660 lie in the dial production:

• Matte Dials: The earliest examples of the 16660 (roughly from introduction to around 1984) featured a matte black dial with painted tritium hour markers.⁵ These are often referred to as “Mark I” and “Mark II” dials by collectors, with subtle differences in the font and coronet. These early versions are highly sought after for their vintage aesthetic.
• Glossy Dials: Around 1984, Rolex transitioned to a glossy black dial with applied hour markers made from white gold, which held the tritium lume.⁶ This change marked a significant step towards the modern Rolex sports watch aesthetic. Some of these glossy dials have developed a “spider” or “craquelure” effect over time, where the lacquer finish develops fine cracks, a feature some collectors find desirable.
• COMEX Dials: A very small number of Reference 16660 watches were issued to the French commercial diving company COMEX (Compagnie Maritime d’Expertises).⁷ These watches feature the COMEX logo on the dial and are exceptionally rare and valuable. Both matte and glossy dial versions with the COMEX logo exist.

The Correct Dial

The “correct” dial for a 16660 depends on its production year. Early models (late 1970s to early 1980s) should have a matte dial with painted tritium markers.⁸ Later models (mid-1980s onwards) should have a glossy dial with applied white gold markers. The tritium lume on original examples will have aged to a creamy or yellowish patina.

The Correct Hands

The Reference 16660 was fitted with the iconic Rolex “Mercedes” hands, filled with tritium lume that should match the patina of the hour markers on the dial.⁹

The Correct Case and Crown

The 40mm stainless steel case of the 16660 is a robust and functional design. It features the signature Rolex Triplock screw-down crown, providing exceptional water resistance.¹⁰ The caseback engravings also saw variations throughout the production run. Early casebacks had “ROLEX” and “OYSTER” engraved in a straight line, while later versions featured a more curved text. The engravings also denoted the “ORIGINAL GAS ESCAPE VALVE” patent.

Additional Details

The introduction of the Caliber 3035 movement was a significant upgrade for the Sea-Dweller line. This high-beat movement (28,800 vibrations per hour) offered improved accuracy and reliability. It also introduced the convenience of a quick-set date function, allowing the owner to adjust the date independently of the time.

The Rolex Sea-Dweller 16660 represents a pivotal moment in the evolution of the professional diver’s watch. Its blend of vintage charm and modern functionality makes it a highly desirable and historically significant timepiece for any serious watch enthusiast.