It consists of the melting with the Uncooked material using oxyhydrogen flame as well as crystallisation with the melted droplets to type a cylinder. Graded 9 to the Mohs-hardness scale (graded 1-ten), the resulting sapphire crystals are practically scratch-proof and really tricky, making certain an unhindered vision at all times. https://www.watchesworld.com/top-10-dive-watches/