Allochromatic gems are gems which might be colored by impurities. Should they had been completely pure, they'd be colorless. The colour of all allochromatic gems is made by defects. Therefore, all coloration in corundum is caused by defects. Delhi is the primary location for gem fans, and it is without https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share