It requires the melting of the raw substance working with oxyhydrogen flame as well as the crystallisation in the melted droplets to variety a cylinder. Graded nine about the Mohs-hardness scale (graded 1-10), the ensuing sapphire crystals are practically scratch-proof and very difficult, making sure an unhindered eyesight constantly. TAG https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/