It involves the melting in the raw substance applying oxyhydrogen flame and the crystallisation with the melted droplets to type a cylinder. Graded nine over the Mohs-hardness scale (graded 1-10), the resulting sapphire crystals are virtually scratch-proof and really tricky, making certain an unhindered vision all the time. Practical cookies https://www.watchesworld.com/top-10-dive-watches/