It consists of the melting of your raw compound using oxyhydrogen flame and the crystallisation of the melted droplets to type a cylinder. Graded nine over the Mohs-hardness scale (graded one-ten), the resulting sapphire crystals are just about scratch-evidence and really tough, making sure an unhindered eyesight all the time. https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/