This study of yellow sapphires was motivated by The dearth of clarity inside the literature as towards the origin with the yellow coloration. In retrospect, this uncertainty was the result of 3 variables. Initially, the Fe3+ concentration in natural stones spans A selection of close to 4–4750 ppma, but only https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share