It includes the melting of the Uncooked material applying oxyhydrogen flame and also the crystallisation in the melted droplets to sort a cylinder. Graded nine about the Mohs-hardness scale (graded one-10), the resulting sapphire crystals are just about scratch-proof and very challenging, guaranteeing an unhindered eyesight all of the time. https://www.watchesworld.com/top-10-dive-watches/