It will involve the melting of your raw substance using oxyhydrogen flame and the crystallisation with the melted droplets to kind a cylinder. Graded 9 over the Mohs-hardness scale (graded one-ten), the resulting sapphire crystals are just about scratch-evidence and really really hard, ensuring an unhindered vision constantly. To ensure https://www.watchesworld.com/top-10-dive-watches/