It will involve the melting from the raw compound applying oxyhydrogen flame as well as crystallisation of your melted droplets to variety a cylinder. Graded 9 about the Mohs-hardness scale (graded one-10), the resulting sapphire crystals are pretty much scratch-evidence and very difficult, ensuring an unhindered eyesight continually. Afterwards illustrations https://www.watchesworld.com/top-10-dive-watches/