Noticeable from the caseback, the oscillating mass with the motion is delicately engraved. It's made from 18-karat gold and decorated by hand which has a barley grain sample, finished by guilloche William’s charting, aided from the H4, correctly predicted landfall at Kingston inside a margin of just one nautical mile- https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/