It consists of the melting from the raw compound working with oxyhydrogen flame plus the crystallisation in the melted droplets to type a cylinder. Graded 9 within the Mohs-hardness scale (graded 1-ten), the resulting sapphire crystals are virtually scratch-evidence and very really hard, ensuring an unhindered eyesight continually. To paraphrase, https://www.watchesworld.com/the-most-coveted-watches-in-the-uk/