It consists of the melting from the Uncooked material using oxyhydrogen flame as well as crystallisation on the melted droplets to kind a cylinder. Graded nine within the Mohs-hardness scale (graded one-10), the resulting sapphire crystals are nearly scratch-proof and really difficult, making sure an unhindered vision at all times. https://www.watchesworld.com/top-10-dive-watches/