It involves the melting with the Uncooked material utilizing oxyhydrogen flame and also the crystallisation on the melted droplets to form a cylinder. Graded nine around the Mohs-hardness scale (graded one-10), the resulting sapphire crystals are nearly scratch-evidence and very hard, making sure an unhindered eyesight all of the time. https://www.watchesworld.com/top-10-dive-watches/