Seen in the caseback, the oscillating mass from the movement is delicately engraved. It really is comprised of eighteen-karat gold and decorated by hand having a barley grain pattern, done by guilloche When your Omega has the words 'Grasp Chronometer' within the dial—as is seen during the Seamaster Diver 300M—you https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/