It involves the melting with the raw substance using oxyhydrogen flame and the crystallisation from the melted droplets to form a cylinder. Graded nine over the Mohs-hardness scale (graded one-10), the resulting sapphire crystals are nearly scratch-proof and really difficult, making sure an unhindered vision all the time. Linkedin set https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/