It consists of the melting on the raw compound utilizing oxyhydrogen flame along with the crystallisation of the melted droplets to kind a cylinder. Graded nine to the Mohs-hardness scale (graded 1-ten), the resulting sapphire crystals are nearly scratch-proof and really hard, ensuring an unhindered eyesight all of the time. https://www.watchesworld.com/top-10-dive-watches/