It entails the melting from the raw compound employing oxyhydrogen flame along with the crystallisation with the melted droplets to variety a cylinder. Graded nine within the Mohs-hardness scale (graded 1-10), the ensuing sapphire crystals are virtually scratch-proof and really tricky, guaranteeing an unhindered vision at all times. Functional cookies https://www.watchesworld.com/top-10-dive-watches/