It entails the melting of the raw compound using oxyhydrogen flame along with the crystallisation in the melted droplets to kind a cylinder. Graded 9 to the Mohs-hardness scale (graded 1-ten), the ensuing sapphire crystals are just about scratch-proof and very tough, ensuring an unhindered eyesight continually. Picture: HICONSUMPTION It https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/