It will involve the melting in the Uncooked compound employing oxyhydrogen flame and the crystallisation from the melted droplets to variety a cylinder. Graded nine to the Mohs-hardness scale (graded one-ten), the ensuing sapphire crystals are pretty much scratch-evidence and very tough, making sure an unhindered vision all the time. https://www.watchesworld.com/top-10-dive-watches/