It entails the melting with the raw substance applying oxyhydrogen flame and the crystallisation of the melted droplets to sort a cylinder. Graded 9 on the Mohs-hardness scale (graded 1-ten), the ensuing sapphire crystals are practically scratch-evidence and really hard, ensuring an unhindered eyesight all the time. Within our quest https://www.watchesworld.com/top-10-dive-watches/