Obvious from the caseback, the oscillating mass in the movement is delicately engraved. It's made from 18-karat gold and decorated by hand which has a barley grain pattern, carried out by guilloche So In the event your Omega has the words and phrases ‘Master Chronometer’ over the dial—as is seen https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/