This study of yellow sapphires was inspired by The dearth of clarity while in the literature as for the origin from the yellow coloration. On reflection, this uncertainty was the result of a few things. First, the Fe3+ focus in natural stones spans A selection of close to four–4750 ppma, https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share