It consists of the melting in the Uncooked compound making use of oxyhydrogen flame plus the crystallisation on the melted droplets to sort a cylinder. Graded nine about the Mohs-hardness scale (graded one-10), the ensuing sapphire crystals are just about scratch-evidence and very tricky, making sure an unhindered vision always. https://www.watchesworld.com/top-10-dive-watches/