It requires the melting of the raw substance working with oxyhydrogen flame and the crystallisation in the melted droplets to sort a cylinder. Graded nine around the Mohs-hardness scale (graded 1-10), the resulting sapphire crystals are practically scratch-proof and very challenging, ensuring an unhindered eyesight always. Our pro reviewers invest https://www.watchesworld.com/top-10-dive-watches/