Visible with the caseback, the oscillating mass with the motion is delicately engraved. It can be produced from eighteen-karat gold and decorated by hand that has a barley grain pattern, accomplished by guilloche If your Omega has the phrases 'Master Chronometer' to the dial—as is observed within the Seamaster Diver https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/