This review of yellow sapphires was inspired by the lack of clarity while in the literature as to the origin from the yellow coloration. In retrospect, this uncertainty was the result of 3 aspects. 1st, the Fe3+ concentration in natural stones spans A variety of close to 4–4750 ppma, but https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share