It entails the melting with the raw material using oxyhydrogen flame as well as the crystallisation in the melted droplets to variety a cylinder. Graded 9 about the Mohs-hardness scale (graded one-10), the resulting sapphire crystals are virtually scratch-proof and very difficult, ensuring an unhindered vision all the time. We https://www.watchesworld.com/top-10-dive-watches/