It entails the melting of the raw compound working with oxyhydrogen flame plus the crystallisation on the melted droplets to kind a cylinder. Graded 9 over the Mohs-hardness scale (graded one-10), the ensuing sapphire crystals are pretty much scratch-proof and really challenging, making certain an unhindered eyesight at all times. https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/