This study of yellow sapphires was inspired by the lack of clarity inside the literature as towards the origin from the yellow coloration. On reflection, this uncertainty was the result of three variables. First, the Fe3+ concentration in natural stones spans a range of approximately four–4750 ppma, but only concentrations https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share