It involves the melting in the Uncooked material making use of oxyhydrogen flame along with the crystallisation in the melted droplets to type a cylinder. Graded 9 around the Mohs-hardness scale (graded one-10), the ensuing sapphire crystals are pretty much scratch-evidence and very really hard, ensuring an unhindered eyesight always. https://www.watchesworld.com/top-10-dive-watches/