It consists of the melting from the raw material applying oxyhydrogen flame plus the crystallisation of the melted droplets to kind a cylinder. Graded 9 to the Mohs-hardness scale (graded 1-10), the ensuing sapphire crystals are practically scratch-proof and very hard, guaranteeing an unhindered vision all the time. Its amazing https://www.watchesworld.com/top-10-dive-watches/