Allochromatic gems are gems which have been coloured by impurities. Should they were completely pure, they would be colorless. The color of all allochromatic gems is made by defects. As a result, all coloration in corundum is a result of defects. Burma has been renowned for creating a variety of https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share