It consists of the melting with the raw material employing oxyhydrogen flame along with the crystallisation of the melted droplets to type a cylinder. Graded 9 around the Mohs-hardness scale (graded 1-10), the resulting sapphire crystals are practically scratch-proof and really difficult, ensuring an unhindered eyesight continually. Our professional reviewers https://www.watchesworld.com/top-10-dive-watches/