Obvious with the caseback, the oscillating mass from the movement is delicately engraved. It's created from eighteen-karat gold and decorated by hand which has a barley grain sample, done by guilloche Should your Omega has the words 'Learn Chronometer' over the dial—as is witnessed while in the Seamaster Diver 300M—you https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/