It will involve the melting from the Uncooked substance applying oxyhydrogen flame as well as the crystallisation from the melted droplets to sort a cylinder. Graded 9 on the Mohs-hardness scale (graded one-ten), the resulting sapphire crystals are pretty much scratch-evidence and very difficult, making sure an unhindered eyesight continually. https://www.watchesworld.com/top-10-dive-watches/