Allochromatic gems are gems that are coloured by impurities. If they had been absolutely pure, they might be colorless. The color of all allochromatic gems is produced by defects. As a result, all coloration in corundum is caused by defects. Require another reason to order our sunny styles? Yellow sapphires https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share