It includes the melting from the raw substance employing oxyhydrogen flame as well as the crystallisation of the melted droplets to type a cylinder. Graded 9 about the Mohs-hardness scale (graded one-10), the resulting sapphire crystals are almost scratch-evidence and really tough, making sure an unhindered vision all the time. https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/