It includes the melting from the Uncooked compound working with oxyhydrogen flame along with the crystallisation on the melted droplets to kind a cylinder. Graded nine over the Mohs-hardness scale (graded 1-10), the resulting sapphire crystals are pretty much scratch-evidence and really challenging, guaranteeing an unhindered vision at all times. https://www.watchesworld.com/top-10-dive-watches/