It entails the melting from the raw substance utilizing oxyhydrogen flame as well as the crystallisation of the melted droplets to sort a cylinder. Graded 9 around the Mohs-hardness scale (graded 1-ten), the resulting sapphire crystals are nearly scratch-proof and very really hard, ensuring an unhindered eyesight continually. Useful cookies https://www.watchesworld.com/top-10-dive-watches/