It involves the melting with the raw substance utilizing oxyhydrogen flame as well as crystallisation in the melted droplets to form a cylinder. Graded nine around the Mohs-hardness scale (graded 1-10), the ensuing sapphire crystals are just about scratch-proof and very tough, making sure an unhindered vision at all times. https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/