It will involve the melting from the Uncooked material utilizing oxyhydrogen flame and also the crystallisation on the melted droplets to sort a cylinder. Graded 9 about the Mohs-hardness scale (graded 1-10), the resulting sapphire crystals are nearly scratch-proof and very really hard, ensuring an unhindered vision at all times. https://www.watchesworld.com/top-10-dive-watches/