Noticeable in the caseback, the oscillating mass on the movement is delicately engraved. It really is made from eighteen-karat gold and decorated by hand using a barley grain sample, performed by guilloche The Diver 300M is on the market in steel or combos of steel and yellow or Sedna gold, https://www.watchesworld.com/understanding-the-complex-world-of-chronometers/