It involves the melting of the Uncooked substance making use of oxyhydrogen flame along with the crystallisation with the melted droplets to form a cylinder. Graded 9 around the Mohs-hardness scale (graded 1-10), the ensuing sapphire crystals are virtually scratch-proof and very tough, making sure an unhindered eyesight continually. Useful https://www.watchesworld.com/top-10-dive-watches/