Seen in the caseback, the oscillating mass in the movement is delicately engraved. It can be produced from eighteen-karat gold and decorated by hand with a barley grain pattern, accomplished by guilloche Should your Omega has the text 'Grasp Chronometer' on the dial—as is witnessed within the Seamaster Diver 300M—you https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/