This review of yellow sapphires was inspired by The dearth of clarity from the literature as towards the origin on the yellow coloration. Looking back, this uncertainty was the result of a few aspects. Initial, the Fe3+ concentration in natural stones spans a range of roughly four–4750 ppma, but only https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share