Allochromatic gems are gems which can be colored by impurities. Should they were absolutely pure, they would be colorless. The colour of all allochromatic gems is produced by defects. Therefore, all coloration in corundum is because of defects. Individuals with strong Libra and Taurus zodiac placements within their birth charts https://listbell.com/story7782175/sri-lanka-yellow-sapphire-an-overview