The Oyster Perpetual Milgauss, the watch par excellence of technological and scientific progress launched in 1956, reconciles strong magnetic fields and chronometric precision.
Created in 1956 for engineers and technicians who are exposed in their work to magnetic fields which disrupt the performance of mechanical watches, the Milgauss was designed to resist strong interference of up to 1,000 gauss thanks to a magnetic shield patented by Rolex protecting the movement. Hence the name of the watch, mille being French for thousand. The Milgauss became known notably as the watch worn by scientists at the European Organization for Nuclear Research (CERN) in Geneva.
A new generation of this watch, introduced in 2007, encompasses all Rolex’s technological and watchmaking expertise. Aesthetically, the new Milgauss stands out with its orange seconds hand shaped like a lightning bolt, which was inspired by the original model. The watch also features a green sapphire crystal, a novelty in watchmaking.
MAGNETIC INTERFERENCETelecommunications, medical technology, the aerospace and electrotechnical industries are just a few of the many areas in which magnetic fields play a particularly important role. Magnetic fields strongly affect the rate of mechanical watches by magnetizing the components in the movement, in particular the escapement and the oscillator, which are responsible for the watch’s precision. Depending on the intensity and the length of exposure to a magnetic field, the movement rate can be negatively influenced and the watch may even stop. The reliability and precision of an ordinary mechanical watch are affected by a magnetic field of 50 to 100 gauss (or 0.01 tesla, according to today’s unit of measure). As a general example, the strength of the magnetic field of an ordinary poster magnet at a distance of 5 mm is around 200 gauss.
HERITAGE AND EVOLUTIONIn 1956 Rolex succeeded in outsmarting the effects of magnetic fields by designing a watch that resists interference of 1,000 gauss (0.1 tesla, or 80,000 A/m) while preserving its exceptional chronometric performance. Today, several innovations contribute to the resistance of this technological gem. The first line of defence is the magnetic shield inside the Oyster case. Made of ferromagnetic alloys, it surrounds and protects the movement. It is engraved with the symbol for magnetic flux density, the letter B with an arrow above it. This invention was patented by Rolex in 1956 and has since been further improved. The second line of defence involves two of the movement’s key components, the oscillator and the escapement, which are made from innovative and pioneering paramagnetic materials.
THE MILGAUSS, SUPERLATIVE CHRONOMETERLike all Rolex watches, each Milgauss is certified as a Superlative Chronometer. This exclusive designation attests that it has successfully undergone a series of tests conducted by Rolex in its own laboratories and according to its own criteria, which exceed watchmaking norms and standards. These tests are carried out on the fully assembled watch, in order to guarantee its superlative performance on the wrist. 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 COSC (Swiss Official Chronometer Testing Institute) – is, therefore, tested a second time by Rolex after being cased, to ensure that it meets criteria for precision that are far more exacting than those for an official chronometer. The tolerance for the average rate of a Rolex Superlative Chronometer is of the order of −2/+2 seconds per day. Its precision is tested by Rolex using an exclusive methodology that simulates the conditions in which a watch is actually worn and is much more representative of real- life experience.
The Superlative Chronometer certification testing is carried out after casing using state-of-the-art equipment specially developed by Rolex. 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 that ensures the watches’ reliability, robustness, and resistance to magnetic fields and shocks.
THE OYSTER CASE, SYMBOL OF WATERPROOFNESSThe Oyster case, guaranteed waterproof to a depth of 100 metres (330 feet), is a paragon of robustness and reliability. The characteristically shaped middle case is crafted from a solid block of particularly corrosion-resistant Oystersteel. The case back, edged with fine fluting, is hermetically screwed down with a special tool that allows only Rolex watchmakers to access the movement. The winding crown, fitted with the Twinlock double waterproofness system, screws down securely against the case. The crystal is made of virtually scratchproof synthetic sapphire. The waterproof Oyster case provides the Milgauss’s high-precision movement with optimal protection.
PERPETUAL CALIBRE 3131The Milgauss is equipped with calibre 3131, a self-winding mechanical movement entirely developed and manufactured by Rolex. Its architecture, manufacturing and innovative features make it exceptionally precise and reliable. It includes state-of-the-art technologies patented by the brand that ensure exceptional resistance to magnetic fields.
The oscillator 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 3131 features a paramagnetic escape wheel made from nickel-phosphorus and has a blue Parachrom hairspring patented and manufactured by Rolex in an exclusive 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 3131 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 a constant source of energy.
The movement of the Milgauss will be seen only by certified Rolex watchmakers, yet it is beautifully finished and decorated in keeping with the brand’s uncompromising quality standards.