Seen in the caseback, the oscillating mass of the motion is delicately engraved. It is actually created from eighteen-karat gold and decorated by hand with a barley grain sample, performed by guilloche If the Omega has the phrases 'Grasp Chronometer' within the dial—as is witnessed while in the Seamaster Diver https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/