It consists of the melting of your raw substance making use of oxyhydrogen flame as well as crystallisation on the melted droplets to form a cylinder. Graded 9 within the Mohs-hardness scale (graded one-10), the resulting sapphire crystals are almost scratch-proof and very hard, making certain an unhindered eyesight constantly. https://www.watchesworld.com/top-10-dive-watches/