It includes the melting with the raw compound using oxyhydrogen flame and also the crystallisation on the melted droplets to sort a cylinder. Graded nine on the Mohs-hardness scale (graded one-ten), the ensuing sapphire crystals are pretty much scratch-proof and very hard, making sure an unhindered vision continually. All OMEGA https://www.watchesworld.com/top-10-dive-watches/