Obvious from the caseback, the oscillating mass of the movement is delicately engraved. It's made from 18-karat gold and decorated by hand by using a barley grain sample, performed by guilloche A paragon of robustness and trustworthiness, the forty mm Oyster situation of the new GMT-Master II is confirmed water-resistant https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/