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, the first watch of its kind. 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 the 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.