Obvious through the caseback, the oscillating mass in the movement is delicately engraved. It's produced from 18-karat gold and decorated by hand having a barley grain pattern, accomplished by guilloche In the event your Omega has the phrases 'Grasp Chronometer' within the dial—as is seen inside the Seamaster Diver 300M—it https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/