It entails the melting of the raw substance utilizing oxyhydrogen flame and also the crystallisation on the melted droplets to type a cylinder. Graded 9 to the Mohs-hardness scale (graded one-10), the resulting sapphire crystals are just about scratch-proof and very really hard, guaranteeing an unhindered vision at all times. https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/