It consists of the melting with the Uncooked substance working with oxyhydrogen flame plus the crystallisation of the melted droplets to type a cylinder. Graded nine about the Mohs-hardness scale (graded one-ten), the resulting sapphire crystals are just about scratch-proof and very tricky, ensuring an unhindered vision all the time. https://www.watchesworld.com/top-10-dive-watches/