Source: Images and content by Rolex. See the original article here - https://newsroom.rolex.com/watches/oyster-collection/yacht-master-ii
BEZEL WITH CERACHROM INSERT OR BEZEL IN 950 PLATINUM
The bidirectional rotatable bezel on the Yacht-Master II in Oystersteel, in the Everose Rolesor version, and in 18 ct yellow gold is equipped with a monobloc Cerachrom insert in blue ceramic, patented by Rolex. This insert is made of an extremely hard, virtually scratchproof ceramic whose colour is unaffected by ultraviolet rays. In addition, thanks to its chemical composition, the high-tech ceramic is inert and cannot corrode. The numerals and inscriptions are moulded in the ceramic and coloured with gold or platinum using a PVD (Physical Vapour Deposition) process.
The Yacht-Master II in 18 ct white gold is fitted with a bidirectional rotatable bezel in 950 platinum. The raised numerals and inscriptions on this version are stamped into the bezel and polished.
THE YACHT-MASTER II, SUPERLATIVE CHRONOMETER CERTIFIED
Like all Rolex watches, the Yacht-Master II is covered by the Superlative Chronometer certification redefined by Rolex in 2015. This exclusive designation attests that every watch leaving the brand’s workshops has successfully undergone a series of tests conducted by Rolex in its own laboratories and according to its own criteria. These certification tests are carried out on the fully assembled watch, after casing the movement, guaranteeing superlative performance on the wrist in terms of precision, power reserve, waterproofness and self-winding. The Superlative Chronometer status is symbolized by the green seal that comes with every Rolex watch and is coupled with an international five-year guarantee.
The precision of every movement – officially certified as a chronometer by the Swiss Official Chronometer Testing Institute (COSC) – is tested a second time by Rolex after being cased, to ensure that it meets criteria for precision that are far stricter than those of the official certification. The precision of a Rolex Superlative Chronometer is of the order of −2/+2 seconds per day – the rate deviation tolerated by the brand for a finished watch is significantly smaller than that accepted by COSC for official certification of the movement alone.
The Superlative Chronometer certification testing is carried out after casing using state-of-the-art equipment specially developed by Rolex and according to an exclusive methodology that simulates the conditions in which a watch is actually worn and more closely represents real-life experience. The entirely automated series of tests also checks the waterproofness, the self-winding capacity and the power reserve of 100 per cent of Rolex watches. These tests systematically complement the qualification testing upstream during development and production, in order to ensure the watches’ reliability, robustness, and resistance to magnetic fields and shocks.
THE OYSTER CASE, SYMBOL OF WATERPROOFNESS
The Yacht-Master II’s Oyster case, 44 mm in diameter and guaranteed waterproof to a depth of 100 metres (330 feet), is a paragon of robustness and reliability. The middle case is crafted from a solid block of Oystersteel, a particularly corrosion-resistant alloy, or 18 ct gold. The case back, edged with fine fluting, is hermetically screwed down with a special tool that allows only certified Rolex watchmakers to access the movement. The Triplock winding crown, fitted with a triple waterproofness system, screws down securely against the case. It is protected by a crown guard that is an integral part of the middle case. The crystal is made of virtually scratchproof sapphire. The waterproof Oyster case provides optimum protection for the Yacht-Master II’s mechanical movement.
PERPETUAL CALIBRE 4161
The Yacht-Master II is equipped with calibre 4161, a self-winding mechanical chronograph movement entirely developed and manufactured by Rolex. The architecture, manufacturing and innovative features of this movement make it exceptionally precise and reliable.
Calibre 4161 was based on the 4130 chronograph movement, which equips the Oyster Perpetual Cosmograph Daytona. It is fitted with a traversing column wheel and vertical clutch for an instantaneous and extremely precise chronograph start.
The oscillator of calibre 4161 has a large balance wheel with variable inertia regulated extremely precisely via gold Microstella nuts. It is held firmly in place by a height-adjustable traversing bridge enabling very stable positioning to increase shock resistance.
Calibre 4161 has a blue Parachrom hairspring, manufactured by Rolex in a paramagnetic alloy. Insensitive to magnetic fields, the Parachrom hairspring offers great stability in the face of temperature variations and remains up to 10 times more precise than a traditional hairspring in case of shocks. It is equipped with a Rolex overcoil, ensuring its regularity in any position.
Calibre 4161 is fitted with a self-winding module featuring a Perpetual rotor, which ensures continuous winding of the mainspring by harnessing the movements of the wrist to provide constant energy. It offers a power reserve of approximately 72 hours. The Yacht-Master II’s movement will be seen only by certified Rolex watchmakers, yet it is beautifully finished and decorated in keeping with the brand’s uncompromising quality standards.
BRACELET AND CLASP, SECURE AND COMFORTABLE
The Yacht-Master II is available on a three-piece link Oyster bracelet that is equipped with a Rolex-designed and -patented Oysterlock safety clasp, which prevents accidental opening. The bracelet is additionally fitted with the Easylink comfort extension link, developed by the brand. This system allows the wearer to easily increase the bracelet length by approximately 5 mm, for additional comfort in any circumstance.