Allochromatic gems are gems which have been coloured by impurities. When they ended up entirely pure, they might be colorless. The color of all allochromatic gems is made by defects. So, all coloration in corundum is due to defects. Delhi is the main location for gem lovers, and it has https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share