It entails the melting in the raw substance employing oxyhydrogen flame as well as the crystallisation of your melted droplets to kind a cylinder. Graded nine about the Mohs-hardness scale (graded one-10), the ensuing sapphire crystals are just about scratch-proof and very challenging, ensuring an unhindered eyesight always. Purposeful cookies https://www.watchesworld.com/top-10-dive-watches/