It includes the melting from the Uncooked substance utilizing oxyhydrogen flame and also the crystallisation of the melted droplets to kind a cylinder. Graded nine to the Mohs-hardness scale (graded 1-10), the resulting sapphire crystals are virtually scratch-evidence and really hard, making certain an unhindered eyesight all of the time. https://www.watchesworld.com/top-10-dive-watches/