It requires the melting on the raw substance using oxyhydrogen flame as well as the crystallisation on the melted droplets to type a cylinder. Graded 9 about the Mohs-hardness scale (graded one-ten), the ensuing sapphire crystals are nearly scratch-evidence and very difficult, ensuring an unhindered eyesight continually. Picture: HICONSUMPTION It https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/