It consists of the melting with the Uncooked compound utilizing oxyhydrogen flame and also the crystallisation of the melted droplets to sort a cylinder. Graded 9 within the Mohs-hardness scale (graded 1-ten), the resulting sapphire crystals are practically scratch-evidence and very tough, making certain an unhindered eyesight at all times. https://www.watchesworld.com/top-10-dive-watches/