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