Gold to Green color changer, Dravite the species oval.#300

Green to gold color changer, Dravite the species Oval  #300 This gemstone appears to be eye clean and with good crystal. It is a color changer from green in daylight, to gold in incandescent light. It has a medium dark tone level and weighs 2.92 carats.

In my opinion this is a true color changer.  I have run into a few on the inter net, but this is the only one in the collection.  I did not realize that I had a another type of color changer when I bought the rough.   I can tell that it is a dravite from the absorption graphs produced by my spectrometer, which look a lot like chrome tourmaline.  But of course chrome tourmaline, which is probably not colored with chrome,  is always green and does not change color.  Which chromophores chrome, vanadium or more I do not know or their concentrations and I wish that I could find something out about it.    The gemstone appears to be eye clean, not dichroic and with good crystal.  It weighs 2.92 carats. and has a medium dark tone level.

Bruce

About Bruce Fry

I was born in Summit, NJ in 1947 and graduated from Summit High School in 1966. I graduated from the Colorado School of Mines in 1970 and after spending another year in graduate school, I left to see the world of Brazil. After spending some more time discovering myself, I ended up working for the Commonwealth of Pennsylvania for 32 years as an Air Quality Engineer in the Department of Environmental Protection. I retired in 2007 and took up faceting gemstones again after a long hiatus that reached back to my twenties. I had started cutting cabochons when I was 13 and bought my first faceting machine when I was 15, but ran out of money and time until I retired. My great love in gemology is tourmaline and the collection presented here represents my effort to get as much beauty and variety in the colors of tourmaline as I can. I was particularly lucky in being able to get unheated cuprian tourmaline before copper was discovered in gem grade tourmaline from Mozambique.
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