The Oyster case is one of the foundations of the reputation for excellence of Rolex watches. Invented by Rolex in 1926, it was the world’s first waterproof case for a wristwatch thanks to its patented system of screwing down the bezel, case back and winding crown against the middle case. Like the mollusc, the Rolex Oyster is robust and clamped shut.
It provides a hermetic environment that protects the high-precision Perpetual movement from water, dust, or pressure.

The name Rolesor was registered in 1933 and today designates the harmonious combination of 18 ct gold and steel on a single watch. Rolex’s first experience with the juxtaposition of two contrasting metals dates back to the 1920s, when Rolex watches were available with a two-tone Bicolore gold case: mostly yellow or red gold paired with white gold or platinum. Three years after the launch of the Oyster Perpetual Datejust in 1945, the model was presented in Rolesor. The use of yellow, Everose, or white Rolesor was gradually extended to other models including watches in the Professional range.

Manufactured by Rolex from an extremely hard ceramic material since 2005, the exclusive Cerachrom bezel insert and monobloc bezel have excellent anti-corrosion properties and keep their vibrant colours over time. They are virtually scratchproof, and are unaffected by exposure to sunlight as well as to chlorinated or sea water. To inscribe the numerals and graduations on such a hard material, Rolex developed a unique process which culminates in their being coated with a thin layer of yellow gold or platinum.
It takes 40 hours to produce each Cerachrom bezel.
At Rolex, no measure is too extreme in the pursuit of beauty and function.

The Triplock winding crown is a patented triple waterproofness system designed especially for divers’ watches. Developed by Rolex, it resists water pressure to depths of 300 metres (1,000 feet) on the Submariner models and some other Professional models, and 3,900 metres (12,800 feet) on the Rolex Deepsea. First introduced in 1970, the Triplock system consists of 10 different elements crafted from the most reliable materials. The winding crown screws down against the Oyster case as tightly and hermetically as a submarine’s hatch.

Rolex sapphire crystals are made of scratch-resistant synthetic sapphire.

The watch case is rigorously tested to ensure it meets pressure-resistance requirements. The three-step process - a vacuum test, a compression test and a condensation test - will reveal the presence of even the smallest amount of moisture inside the case.

The Yacht-Master II is equipped with calibre 4160, a self-winding mechanical regatta chronograph movement entirely developed and manufactured by Rolex. The result of over 35,000 hours of development, the Yacht-Master II introduces a new regatta countdown with a unique, patented mechanical memory created by Rolex. A number of the 360 components in the 4160 movement are so tiny or complex that they can only be made by new, cutting-edge technology. Like all Rolex Perpetual movements, the 4160 is a certified Swiss chronometer, a designation reserved for high-precision watches that have successfully passed the Swiss Official Chronometer Testing Institute (COSC) tests. Its architecture, in common with all Oyster watch movements, makes it singularly reliable.

The four simple words Superlative Chronometer Officially Certified on a Rolex watch dial mean that the very movement inside the timepiece has endured 15 days and nights of testing by COSC (Contrôle Officiel Suisse des Chronomètres – Swiss Official Chronometer Testing Institute), an independent not-for-profit association. To receive COSC certification as a Swiss chronometer, a watch must demonstrate extreme precision in a variety of positions and temperatures. Rolex is unique in the industry: this is the standard level of quality required of every Rolex wristwatch movement.

In a mechanical watch, the oscillator is the guardian of time. Conventional oscillator hairsprings are made of ferromagnetic alloys, leaving them vulnerable to magnetic fields, temperature variations and shocks that interfere with their precision. After years of research, Rolex created the blue Parachrom hairspring, which is finer than a human hair. Crafted from a highly stable paramagnetic alloy that includes niobium and zirconium, it is insensitive to magnetic fields and up to 10 times more resistant to shocks. Historically, the unique blue colour of the hairspring has been a sign of prestige reserved for only the most accurate timepieces.

Invented by Rolex in 1931, this ingenious mechanism harnesses the energy of natural wrist movements to provide a reliable and clean source of power for the watch movement. It consists of a half-moon- shaped oscillating weight, which pivots freely in both directions on its axle. As it rotates, the rotor continuously winds the Perpetual movement’s mainspring, ensuring a constant and stable source of energy. This enhances the watch’s precision and eliminates the need to wind it regularly. The Perpetual rotor mechanism features two distinctive red reversing wheels, which ensure efficient winding of the movement regardless of the direction in which the oscillating weight rotates.

The name Rolesor was registered in 1933 and today designates the harmonious combination of 18 ct gold and steel on a single watch. Rolex’s first experience with the juxtaposition of two contrasting metals dates back to the 1920s, when Rolex watches were available with a two-tone Bicolore gold case: mostly yellow or red gold paired with white gold or platinum. Three years after the launch of the Oyster Perpetual Datejust in 1945, the model was presented in Rolesor. The use of yellow, Everose, or white Rolesor was gradually extended to other models including watches in the Professional range.