It entails the melting on the raw material using oxyhydrogen flame as well as the crystallisation of the melted droplets to type a cylinder. Graded nine about the Mohs-hardness scale (graded 1-ten), the resulting sapphire crystals are nearly scratch-proof and really tricky, ensuring an unhindered vision all of the time. https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/