Allochromatic gems are gems which can be colored by impurities. If they were being fully pure, they would be colorless. The colour of all allochromatic gems is made by defects. Thus, all color in corundum is a result of defects. Known for its clarity and shading uniformity, the Burmese Yellow https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share