It consists of the melting on the Uncooked compound using oxyhydrogen flame as well as the crystallisation from the melted droplets to kind a cylinder. Graded 9 on the Mohs-hardness scale (graded one-10), the ensuing sapphire crystals are almost scratch-proof and very difficult, guaranteeing an unhindered vision at all times. https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/