It will involve the melting on the raw compound working with oxyhydrogen flame plus the crystallisation from the melted droplets to form a cylinder. Graded nine about the Mohs-hardness scale (graded 1-10), the ensuing sapphire crystals are nearly scratch-proof and really tough, making sure an unhindered vision all the time. https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/