It entails the melting from the raw material working with oxyhydrogen flame and also the crystallisation on the melted droplets to kind a cylinder. Graded 9 on the Mohs-hardness scale (graded 1-10), the resulting sapphire crystals are virtually scratch-evidence and really tough, making sure an unhindered vision at all times. https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/