This research of yellow sapphires was inspired by The dearth of clarity within the literature as to your origin on the yellow coloration. On reflection, this uncertainty was the result of three things. Initial, the Fe3+ concentration in natural stones spans A selection of somewhere around 4–4750 ppma, but only https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share