It entails the melting with the raw substance applying oxyhydrogen flame along with the crystallisation of the melted droplets to type a cylinder. Graded 9 over the Mohs-hardness scale (graded one-ten), the resulting sapphire crystals are just about scratch-proof and very tough, making sure an unhindered eyesight continually. Significantly useful https://www.watchesworld.com/top-10-dive-watches/