Obvious throughout the caseback, the oscillating mass of your movement is delicately engraved. It can be produced from 18-karat gold and decorated by hand with a barley grain sample, completed by guilloche If your Omega has the words and phrases 'Master Chronometer' to the dial—as is viewed within the Seamaster https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/