The publication of a new study on the principle and trace elements in Paraiba/ cuprian tourmaline in The Journal of Gemmology, along with changes’s in The Guide’s presentation of how the market values copper bearing tourmaline has me troubled. The study really adds very little to the understanding of color in cuprian tourmaline. The authors do discuss what might be causing some copper bearing tourmaline to be green. Their conclusion that there is not enough titanium in most copper bearing tourmaline to make valance charge transfer reaction with manganese a factor in coloring copper bearing tourmaline and only a limited number have enough iron to make them green is not new, but very reasonable. The discovery of a few copper vanadium colored tourmaline is more of another example of the complexity of color on tourmaline then an answer to what makes some copper bearing tourmaline green. At least they did not claim that the color gradation between blue to green is a response to changes in the concentration of copper, like many casual writers about copper bearing tourmaline seem to infer.
The dividing of the world of copper bearing tourmaline into two charts by The Guide is reasonable as far as it goes. Paraiba tourmaline, as The Guide defines it, certainly lives in its own world of prices. But to put both Paraiba type material from locations other than Brazil and many other colors of cuprian together is ridiculous. It has lead to prices of high grade cuprian tourmaline to decrease as the gemstone’s size goes up. This may make sense for Paraiba like stones that are in demand, if they resemble some grade of Paraiba, but not the other colors. (Paraiba tourmaline is usually both small and included.)
A final concern that I have stated many times before. No matter what modifies the basic blue color of tourmaline containing copper +2 valance state or its size and clarity, if it does not have that vivid glow like quality in its soul, I wouldn’t pay the high prices for it. (That includes the wonderful color of pure copper +2 that can be duplicated by iron) Keep focused on the beauty of the gemstone not its chemistry or its place of birth.
Bruce
