Allochromatic gems are gems that are coloured by impurities. When they have been absolutely pure, they'd be colorless. The color of all allochromatic gems is produced by defects. Consequently, all colour in corundum is attributable to defects. Have to have another excuse to obtain our sunny designs? Yellow sapphires will https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share