It entails the melting of the raw compound working with oxyhydrogen flame plus the crystallisation on the melted droplets to kind a cylinder. Graded nine within the Mohs-hardness scale (graded 1-ten), the ensuing sapphire crystals are almost scratch-proof and really tricky, making sure an unhindered eyesight all of the time. https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/