What you need to know about Rolex Oyster cases that you can't ask now

One of the most revolutionary and historic wristwatch inventions is the Rolex Oyster case. There are certain reasons behind the success of continuing to walk the sunny road. In this article, we will reexamine various aspects of the Oyster case that remain in watch history and re-examine its capabilities.

Originally published on watchtime.comText by Mark Bernardo December 7, 2021

The Oyster, a cornerstone of Rolex's fame since 1926

The Sea-Dweller, developed by Rolex as a tool for deep-sea expeditions . Born in 1967, it has been a driving force in Rolex divers' watches for many years.

To understand why Rolex has become the steadfast place it is today, one has to consider its long history and masterful craftsmanship. Among the many innovations and creations that Rolex has brought to the watch industry, the Oyster case is particularly noteworthy.

Developed in 1926, the Rolex Oyster (as it was called by the brand at the time) was a practical waterproof and dustproof watch case that revolutionized the watch industry in many ways. This transformed the wristwatch from a delicate timepiece worn by women to a robust accessory worn by men as well. The characteristics of the Oyster case, which has become a symbol of robustness and water resistance, have been proven over time, and the letters "Oyster" are written on the dials of watches shipped from the Rolex workshop.

The first Rolex Oyster from 1926, reference 679.

Rolex Oysters come with sealed cases, winding crowns, cyclops lenses, fixed or rotating fluted bezels, helium escape valves on the Sea-Dweller and Rolex Deepsea, and today, Chromalight displays. ing. Knowing the various aspects of the Oyster case will help you better understand why it is one of the watch industry's most important inventions.

Rolex Oyster cases are hermetically sealed, ranging from 100m (330ft) to 300m (1000ft) for the Submariner and Submariner Date, 1220m (400ft) for the Sea-Dweller and 3900m (12,800ft) for the Rolex Deepsea. feet) waterproof. The Oyster case also features a middle case that is stamped and machined from a block of Oystersteel, 18K gold or platinum 950. This serves as an important framework for the case, supporting the entire structure of the case and greatly increasing its robustness. The crown guard, which is often used in professional models, is provided on the side of the middle block and is integrated with the case structure. The sapphire crystal is mounted on gaskets along the edge of the case, further enhancing the water and dust resistance of the Oyster case. The caseback has a screw-down caseback that is attached with a special tool. Only Rolex engineers have access to the interior, further enhancing security against tampering.

Twinlock crowns introduced in 1953 and Triplock crowns introduced in 1970 are patented features developed to ensure the high water resistance of the Oyster case. It was the development of the Oyster case that earned Rolex watches its reputation for having an efficient waterproof case structure.

In addition to the former consisting of a double sealing system (one inside the tube and one inside the crown), the latter adds another sealing part inside the tube (inside the tube). 2 locations, 1 location inside the crown). This is stamped on the crown top with the Rolex emblem, and in the case of the Twinlock it can be a dot, two dots or a line. Triplocs are identified by three dots. Used in divers' watches such as the Submariner, Submariner Date, Sea-Dweller and Rolex Deepsea, they consist of about 10 parts and provide maximum water resistance, similar to the seal of a submarine's hatch. there is Twinlock and Triplock materials include Oystersteel, 18K gold and platinum 950.

Triplock crown with three dots.

One of the distinguishing features of the Oyster case is the presence of the "Cyclops" lens on the sapphire crystal. Its name is derived from the one-eyed giant in Greek mythology, and the Cyclops Lens appeared in the early 1950s. Its main function is to magnify the date display. By adding this to the windshield, the visibility of the date is dramatically improved. Given the success its uniqueness and innovation had earned, Rolex was quick to warn other brands through the newspapers of the time against other brands trying to incorporate similar features. "A note to all watchmakers: watch crystals with specially shaped magnifying lenses are exclusive Rolex products in Switzerland and elsewhere. Do not hesitate to take legal action against counterfeit products." ”.

Over the years, Cyclops lenses have become an aesthetic feature of many Rolex models. In addition, there has been a shift from Plexiglas, in which the lens and crystal are integrated, to sapphire crystal with anti-reflective treatment on both sides.

The Oyster case, which has excellent water and dust resistance, is mainly used in diver's watches. Therefore, it was necessary to have a function that would maintain visibility even in dark places such as underwater. To meet this demand, since 2008 Rolex has been using an innovative phosphorescent material called Chromalight. This material, which glows blue, enhances visibility in the dark and can extend the visibility time. Employed in the hands, hour markers and other display elements of most of the Oyster collection watches, this high performance luminous material allows the wearer to easily check the time even in the dark. Chromalight display lasts for more than 8 hours, about twice as long as general phosphorescent paint.

The Yacht-Master's dial is easy to read day or night, thanks to its strong black-and-white contrast and blue Chromalight luminescence.

The helium escape valve, commonly found on the Sea-Dweller and Rolex Deepsea, serves to relieve the pressure inside the watch case during the decompression phase. This is done in a pressurized space without sacrificing the water resistance of the watch. Developed and patented by Rolex in 1967, this revolutionary feature soon became an important part of the world of deep diving. The existence of the helium escape valve allowed divers to dive deeper and spend more time underwater. Like saturation diving, the watch that accompanied the diver was equipped with the ability to release the helium that the watch had absorbed.

So how does it work? The helium escape valve on the side of the case consists of a closed cylinder with a piston surrounded by a spring. If the pressure difference between the inside and outside of the watch is less than 2.5 atmospheres, the piston remains closed. Once that number is exceeded, the piston will automatically move to release the excess pressure built up inside.

A helium escape valve prevents the watch's crystal from breaking during the diver's decompression phase.

When Rolex was in the development stage of the Oyster case, the bezel was one of the most visible and most exposed parts to external influences such as shock, scratches and corrosion, in addition to the robustness of the case. I knew there was. For this reason Rolex has developed Cerachrom bezel inserts and Cerachrom bezels for some Professional models in the Oyster collection. It is made of ceramics with excellent corrosion resistance, and is extremely hard, so it has excellent scratch resistance and prevents fading due to ultraviolet rays. It also has excellent polishability and maintains a beautiful luster for a long time.

The Cerachrom bezel insert was featured in the GMT-Master II, introduced in 2005, and today it is also found in the Yacht-Master and Yacht-Master II, the diver's watches Submariner, Submariner Date, Sea-Dweller and Rolex Deepsea. there is Depending on the watch, it has a black, blue or green ceramic bezel insert.

The raw ceramics are very fine zirconium dioxide or aluminum oxide powders consisting of fine particles less than 1 micron (1/1000th of a millimeter) in diameter.

Rolex has expanded the use of the Cerachrom bezel, and in 2013 the Cosmograph His Daytona was the first to feature his Cerachrom monobloc bezel. Like the Cerachrom bezel and the Cerachrom bezel insert, the monobloc Cerachrom bezel is also extremely resistant. Today it is also made in chestnut brown or black ceramic. Rolex has also worked on expanding the color variations. In 2013, the GMT-Master II was offered in blue and black with the first two-color integrated Cerachrom bezel insert, and in 2014, the 18K white gold model was offered in red and blue. In 2018, two colors of brown and black were announced.

The two-color Cerachrom bezel insert is brought about by changing the color of the ceramic half of the insert. This was accomplished by infiltrating the insert halves with various aqueous compound solutions.

All Rolex models undergo a rigorous waterproof test. Immerse each case in water and apply pressure 10% higher than the guaranteed depth. In the case of a diver's watch, the pressure is 35% higher.