It requires the melting of the raw compound working with oxyhydrogen flame plus the crystallisation of the melted droplets to kind a cylinder. Graded 9 over the Mohs-hardness scale (graded one-10), the resulting sapphire crystals are pretty much scratch-proof and very challenging, ensuring an unhindered eyesight at all times. Stainless-steel https://www.watchesworld.com/top-10-dive-watches/