It requires the melting of the raw substance working with oxyhydrogen flame and also the crystallisation from the melted droplets to variety a cylinder. Graded 9 within the Mohs-hardness scale (graded 1-10), the ensuing sapphire crystals are nearly scratch-proof and very hard, guaranteeing an unhindered vision at all times. We https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/