Yellow sapphire is one of the hot selling gemstone in India. The sources of natural yellow sapphires are burma, srilanka, madagascar, thailand, nigeria, australia, tanzania. the major cutting polishing centers are srilanka, thailand, and india.since the supply is less and demand is huge most light coloured sapphires are turned into deep yellow gems. the images will give u a visual idea of how much difference can be achieved by doing gem treatments. many gems become more beautiful and wearable after treatments. but the problem arises when the supplier doesnt disclose the type of treatment done, and also certain unethical labs help them by not disclosing the treatments in their reports. the major type of treatment are glass filling, beryillium heat treatment, irradiation, non additive heat, and finally untreated natural yellow sapphires.