It consists of the melting of the Uncooked compound applying oxyhydrogen flame plus the crystallisation of the melted droplets to type a cylinder. Graded nine within the Mohs-hardness scale (graded one-ten), the ensuing sapphire crystals are just about scratch-proof and very tough, making sure an unhindered eyesight always. Useful cookies https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/