This research of yellow sapphires was motivated by The dearth of clarity while in the literature as to your origin with the yellow coloration. On reflection, this uncertainty was the results of 3 factors. Initially, the Fe3+ focus in natural stones spans a range of somewhere around four–4750 ppma, but https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share