It consists of the melting on the raw material utilizing oxyhydrogen flame along with the crystallisation from the melted droplets to type a cylinder. Graded nine to the Mohs-hardness scale (graded one-10), the ensuing sapphire crystals are virtually scratch-evidence and really tricky, making certain an unhindered vision all the time. https://www.watchesworld.com/top-10-dive-watches/