Allochromatic gems are gems that happen to be colored by impurities. When they have been totally pure, they might be colorless. The colour of all allochromatic gems is produced by defects. Thus, all color in corundum is because of defects. The Srilankan Yellow Sapphire gemstone escalates the knowing and harmony https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share