It will involve the melting with the raw compound applying oxyhydrogen flame along with the crystallisation on the melted droplets to sort a cylinder. Graded nine over the Mohs-hardness scale (graded one-ten), the ensuing sapphire crystals are almost scratch-evidence and really tough, ensuring an unhindered eyesight always. Our professional reviewers https://www.watchesworld.com/top-10-dive-watches/