Milgauss

The Milgauss was Rolex's watch for environments where magnetic fields could interfere with a mechanical movement. Introduced in 1956, it was designed to resist fields of 1,000 gauss. Its name combines mille, French for a thousand, with the unit of measurement.

That purpose led to an internal shield around the movement. Unlike a diver's rotating timing ring, the important equipment was hidden. Rolex says researchers at CERN tested the watch, giving the model a documented connection with scientific work.

Its appearance was less consistent than that of the Submariner or Explorer. The early 6541 had a lightning-bolt seconds hand and a textured dial. The later 1019 used a straighter hand and a plainer face. The function persisted while the visual shorthand for electricity came and went.

When Rolex revived the Milgauss in 2007, it brought the lightning bolt back in orange. The case was now 40 millimeters, and the GV version added green-tinted sapphire glass. A blue-dial GV followed in 2014.

The colored glass is not the magnetic shield. Neither is the orange hand a piece of measuring equipment. Those details give the revived watch a conspicuous identity; the shielding remains inside the case, around the movement.