This study of yellow sapphires was determined by the lack of clarity from the literature as to the origin of your yellow coloration. In retrospect, this uncertainty was the result of a few elements. 1st, the Fe3+ focus in natural stones spans a range of approximately 4–4750 ppma, but only https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share