Pretty strong materials, ideal for gem security (prongs never bend or split conveniently) Could be costly By subtracting different quantities of the h•-Fe3+ absorption spectrum from the spectrum in the 2nd measurement area, we could decide that its focus is approximately 6 ppma, the highest value measured To this point. https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share