Copper Diffusion: Is It Gemology's New Worst Nightmare? Part II

An exceptional emerald crystal:This month’s feature on the R. W. Wise website is an exceptional Colombian emerald crystal. It was found at the La Pita Mine, part of a complex of mines of the same name that I visited during my last buying trip to Colombia.Historically gems of this quality were found at the old mines like Muzo and El Chivor. Chivor was appropriated by Spanish conquistadors in 1550;