This review of yellow sapphires was motivated by the lack of clarity during the literature as to your origin of the yellow coloration. In retrospect, this uncertainty was the result of a few factors. 1st, the Fe3+ focus in natural stones spans a range of close to 4–4750 ppma, but https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share