Visible throughout the caseback, the oscillating mass from the motion is delicately engraved. It is actually produced from eighteen-karat gold and decorated by hand that has a barley grain pattern, performed by guilloche If your Omega has the phrases 'Grasp Chronometer' over the dial—as is viewed during the Seamaster Diver https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/