Allochromatic gems are gems that happen to be colored by impurities. Should they were wholly pure, they'd be colorless. The color of all allochromatic gems is made by defects. Therefore, all color in corundum is attributable to defects. After lighting an incense stick in front of the gemstone the mantra https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share