Allochromatic gems are gems which have been colored by impurities. If they ended up entirely pure, they would be colorless. The color of all allochromatic gems is made by defects. Consequently, all coloration in corundum is attributable to defects. Delhi is the leading spot for gem fans, and it is https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share