Visible through the caseback, the oscillating mass from the movement is delicately engraved. It is created from eighteen-karat gold and decorated by hand which has a barley grain sample, accomplished by guilloche In case your Omega has the text 'Grasp Chronometer' over the dial—as is found inside the Seamaster Diver https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/