A galaxy of flashing stars in aqua blue heaven, oval

Included aqua blue oval #101 This oval's flash is effected by a multitude of tiny inclusions and a few feathers. Still its bright, medium light tone, aqua blue color makes the stone an eye grabber. It weighs 1.46 carats.

To me blue is a hue/color in tourmaline that is a complex issue.  It is  really not solved by limiting Indicolite or Indigolite (I hope I spelled that right because it is a name I never use) to pure blue tourmaline.  (keeping blue greens in their place) Or the use of a place name, Paraiba, for blue derived from copper as a chromophore (trace element that induces color in a gemstone).  There is a whole world out there of blue tourmaline in light to medium pastels that are not dichroic or dark like most indicolite and certainly don’t have the neon look or copper content of Paraiba.  Some material, principally from Afghanistan and Pakistan that have the identical color of Paraiba, but neither the intense neon brightness of copper or the copper content of Paraiba, have found a home under Paraiba like.

The issue of nomenclature for blue tourmaline really begins to fall apart with the growing realization that not all copper bearing tourmaline from either Brazil (a more general location that is still permitted to call itself Paraiba, if the tourmaline has  the correct properties) or Mozambique (I really don’t have much impute about Nigerian) have a neon look at all.  I don’t know of any serious discussion of this problem with the definition of Pariaba, paraiba type and paraiba like  tourmaline.  I have tried to take a few baby steps to look at it.

I have used my spectrometer to test for copper absorption in both blues (Mozambique) that have a good neon look and those that do not.  I don’t have a lot of specimens, but the little I can see does not indicate a large difference in the absorption peaks, in the range of copper absorption, between the two types of cuprian blue.  This is trying to compare gemstones with equal tonal values and hues which makes my choices very crude and limited.  My biggest limitation is the lack of information on the gemstones copper and iron content.  The iron content and its electronic state is important because iron can produce at least a part of the absorption curve of copper.  My spectrometer can still easily separate them, but a mixture of the right form of iron and copper could be a problem as to which is dominant.

I think this has the potential of being similar to the problem the Trade faces with Chrome tourmaline.  A test with a filter that is a surrogate for my spectrometer shows the presence of chrome, but does not rule out the dominance of vanadium as the coloring chromophore.  This has lead to the interesting phenomenon of two green tourmalines that look identical by eye, having very different prices because the filter test for chrome shows the presence of the element in the expensive tourmaline while vanadium alone has to color the less expensive one.  Only an actual chemical analysis can show, in the gemstones the pass the filter test, whether chrome or vanadium is the dominant coloring agent.

Now a return to the posted gemstone, which is a modest, yet attractive medium light blue that I call aquamarine because the color is much better known and defined by the Trade in beryl than tourmaline.   The lack of a good tourmaline name for a whole world of tourmaline, similar to this gemstones, lead to this discussion of blue and it nomenclature.   I don’ think the trade is ready to call this gemstone’s color paraiba like and it really does work well with Indicolite (like the difference between pink and red).  The posted gemstone is loaded with a galaxy of fine inclusions, but is still bright and flashy. It is not dichroic in any way visible to the eye.  A rather pretty piece of eye candy that weighs 1.46 carats.

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.
This entry was posted in Indicolite and tagged , , , , . Bookmark the permalink.

Leave a Reply