This review of yellow sapphires was inspired by the lack of clarity in the literature as to your origin from the yellow coloration. In retrospect, this uncertainty was the results of a few things. First, the Fe3+ focus in natural stones spans a range of approximately four–4750 ppma, but only https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share