It will involve the melting from the raw material making use of oxyhydrogen flame and also the crystallisation with the melted droplets to type a cylinder. Graded nine around the Mohs-hardness scale (graded 1-ten), the ensuing sapphire crystals are practically scratch-proof and very really hard, ensuring an unhindered vision always. https://www.watchesworld.com/top-10-dive-watches/