The first Rolex Milgauss was introduced in 1956. The name Milgauss is derived from the Latin mille, which means one-thousand, and gauss, the unit of a magnetic field. This model is so named because it can withstand a magnetic flux density of 1,000 gauss.
According to the Rolex Forum, these green sapphires are made using the Hydrothermal method. It is based on the transformation of melting crashed sapphire and copper together at 600 degrees under the pressure of 800 PSI in order to obtain the optimal green tint. The process takes 4 weeks. Legend!