The reliability and precision of an ordinary mechanical watch can be affected by a magnetic field of 50 to 100 gauss. But many scientists are exposed to much higher magnetic fields during the course of their work. Rolex’s solution was the Rolex Milgauss, created in 1956, and resistant to 1000 gauss. Hence the name of the watch, mille being French for thousand.
The first innovation at the heart of the Milgauss' resistance to magnetic interference is the shield inside its Oyster case. Made of ferromagnetic alloys selected by Rolex, it surrounds and protects the movement. The symbol for magnetic flux density – the capital letter 'B' with an arrow – is engraved in this magnetic shield, but only Rolex-certified watchmakers will ever see it.
The Milgauss is equipped with calibre 3131, a self-winding mechanical movement entirely developed and manufactured by Rolex. It incorporates state-of-the-art technologies patented by the brand that ensure exceptional resistance to magnetic fields. Like all Rolex Perpetual movements, the 3131 is a certified Swiss chronometer, a designation reserved for high-precision watches that have successfully passed the Swiss Official Chronometer Testing Institute (COSC) tests.
A unique watch crystal in green sapphire developed in 2007 by Rolex. Scratchproof, fade-proof and available exclusively on the Milgauss. Its light green shade, tinted throughout the entire crystal, turns nearly luminescent at the bevelled edges. The result of a secret process that required years of development to master and takes weeks to produce. Not patented, as it is so difficult to make that no one else would even venture to try.