Visible from the caseback, the oscillating mass from the motion is delicately engraved. It can be constructed from 18-karat gold and decorated by hand using a barley grain pattern, finished by guilloche A paragon of robustness and reliability, the 40 mm Oyster scenario of the new GMT-Grasp II is confirmed https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/