This study of yellow sapphires was determined by the lack of clarity in the literature as towards the origin from the yellow coloration. Looking back, this uncertainty was the results of 3 aspects. To start with, the Fe3+ concentration in natural stones spans a range of close to four–4750 ppma, https://wildbookmarks.com/story18211273/the-best-side-of-sri-lankan-yellow-sapphire