It consists of the melting with the Uncooked substance employing oxyhydrogen flame along with the crystallisation with the melted droplets to variety a cylinder. Graded 9 within the Mohs-hardness scale (graded 1-ten), the resulting sapphire crystals are nearly scratch-proof and very challenging, guaranteeing an unhindered eyesight all of the time. https://www.watchesworld.com/top-10-dive-watches/