This research of yellow sapphires was determined by the lack of clarity inside the literature as to the origin with the yellow coloration. On reflection, this uncertainty was the result of three elements. 1st, the Fe3+ focus in natural stones spans a range of somewhere around four–4750 ppma, but only https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share