It will involve the melting on the raw compound utilizing oxyhydrogen flame as well as crystallisation of the melted droplets to sort a cylinder. Graded 9 about the Mohs-hardness scale (graded one-ten), the ensuing sapphire crystals are almost scratch-proof and very tough, making certain an unhindered eyesight at all times. https://www.watchesworld.com/top-10-dive-watches/