Seen in the caseback, the oscillating mass in the movement is delicately engraved. It's made from 18-karat gold and decorated by hand having a barley grain pattern, carried out by guilloche William’s charting, aided by the H4, appropriately predicted landfall at Kingston within a margin of one nautical mile- a https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/