It includes the melting with the raw compound employing oxyhydrogen flame along with the crystallisation from the melted droplets to sort a cylinder. Graded nine to the Mohs-hardness scale (graded 1-ten), the ensuing sapphire crystals are just about scratch-proof and very tricky, making sure an unhindered vision all the time. https://www.watchesworld.com/top-10-dive-watches/