Obvious with the caseback, the oscillating mass in the motion is delicately engraved. It really is constructed from 18-karat gold and decorated by hand with a barley grain pattern, finished by guilloche A paragon of robustness and dependability, the forty mm Oyster case of the new GMT-Learn II is confirmed https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/