Crusty, Completely Baked Opinions About Tourmaline

Now I have been on the internet again so I have been confounded again.  At one time in my tourmaline career I use to ride out on my white horse to try and slay seductive, viral, self serving expressions of truth about tourmaline that are not true.  I had some success, but most of the time a contrary idea could not stand up to literally a sea of sites the regurgitated the same information in a most credible fashion.  Well I have begun to write a page on truth in tourmaline that is an honest attempt to set somethings straight based on my investigations and observations using my collection of tourmaline and other sources.  This paragraph is an introduction to a more delicate subject, opinions about the beauty of tourmaline.  Of course beauty is in the eye of the beholder and is subjective etc., so if you read on you will be subject to my opinions.  I just wish I could share my collection with you and let you make up you own mind.  The pictures help, but the collection is an experience that demands time and intimacy.

I keep being told that there are daytime gems and nighttime gems and even some blessed gems that are stable and beautiful under both daytime conditions and nighttime conditions.   Now I can’t take exception to that concept, but when I read that ALL tourmaline are daylight gems or that ALL greens and blues are either daylight gems or nighttime gems I am confounded, befuddled and bemused (as my father use to say).  My opinion is that you must look at the individual tourmaline gemstone in question, under all reasonable white lights, to appreciated its individual personality and beauty.  In the next paragraph I will discuss green in tourmaline with a specific example that I just finished cutting and an older pastel glory, but I think you can expand the concept for my opinion, to all colors of tourmaline.

The range of green in tourmaline is as broad as it can be.  Every shade from blue with just a touch of green to yellow with just a touch of green can be found.  (a long with every green shade in between) The tonal range can be from the slightest wisp of green to a dense black that can only express its green color in thin slices.   And to complete the package, its saturation, or purity of color covers the complete gamut.  To add to this wonderful world of color in tourmaline, we must factor in that tourmaline has at least three major worlds of green color caused by different chromophores.  The most common is caused by trace amounts of iron in tourmaline,  while chrome/vanadium in dravite/uvite (species of tourmaline)probably produces a green that is the most similar to emerald.  Not to be left out is the late blooming cuprian tourmaline (copper bearing) that in some levels of color and tone and saturation can be called Paraiba (location matters too).  One more property of all colors should be mentioned before a brief example of how different white lights effects the  green in two stones in my collection.  That is metamerism and the way we see color depends on colors changing under different white light sources.  Since each chromophore in tourmaline has its own sensitivity to changes in white light, two green tourmaline that might have match each other in color, under one light source could look significantly different under a different white light source.  Differences that could affect the perception of beauty.

Now a simple comparison between a couple of tourmalines I just finished and a special tourmaline I have had for some years.  The tourmalines I just finished (2013) have an outstanding blue green a/b axis and a fine c axis that is significant darker than the a/b and is not nearly as bright.  I hated not to be able to orient the gemstones, I cut, so that the a/b axis could be accented, but that is just the way it was.  I hoped that at least the a/b color would infiltrate the green c axis color enough to give it life.  Well when I saw the finished gems under artificial light, they flashed with a level of saturation  and tone that approached cuprian in its glory.  But when I took them for a walk under  gray and even sunny skies, the gemstones loose their edge and become rather ordinary.

Now I have chosen a unique gemstone in the collection to show the flip side of the previous example about tourmaline, being a daytime or nighttime gemstone because I have a nice story to go along with it.  I could have certainly used other ones.

I was trying to show off my collection under less than ideal conditions of both lighting and time considerations.  I was choosing the best and most interesting when she exclaimed about an exceptionally beautiful gemstone in the tray we were working with.  Had I missed something tantalizing and I quickly looked down.  Well I will be,  there was this watermelon style tourmaline that I had cut with its pink core parallel to the sides of an emerald cut that continues to be border by green sides and it was spectacular.  Its pastel nature had absorbed the fading rays of sun that had already gone behind the hills and was truly beautiful without any need to elevated it with a story of its rarity.

So there you have an exceptional green in artificial light tempered by daylight and a rather modest pastel gemstone elevated to greatness by the defused light of a sun already resting behind the hills.  I could give numerous examples from my collection of tourmaline, but I think this is enough to debunk a statement concerning the uniform beauty or not,  of daytime or nighttime  color in tourmaline, that is too broad and inclusive to be accepted.

Bruce

Inclusions in Tourmaline

Collectors and lovers of tourmaline should be tolerant of inclusion in tourmaline to appreciate the full glory of tourmaline color. This opinion has grown up over the years of cutting tourmaline, in part out of necessity and in part out of a growing appreciation of the properties of tourmaline.

I am not saying that any level of inclusions and flaws are acceptable.  In fact I will list some criteria that I use to judge whether a gemstone will suffer from  cleanliness issues.

1,  The inclusions should not be under the table of the gemstone.

2,  Any residual feathers should be perpendicular to the table.

3,  Any residual inclusions should not flash and be distracting.

4,  Growth tubes should be small in diameter and oriented vertically to the table.

5.  The quality of crystal should be high enough that the finished gemstone is not cloudy.

I use the criteria in the purchase of rough and particularly in the orientation of rough during the preforming stage.  As I have sought out a wider variety of colors in tourmaline I have accepted more included rough.  The challenges presented by this rough have been meet by sacrificing yield and I don’t know how economic the effort its at times.  But the beautiful colors that I see in the quality stones,of my collection, make it all worth while.  It is amazing how a well polished tourmaline with fine color can carry the day with significant inclusions that are oriented properly.  One disconcerting thing is the ability of digital photography to pick up inclusions like a microscope and far in excess of what the eye can do.  Still the eye rules for me and it is my opinion that you can not get the benefit of color in tourmaline without accepting imperfect gemstones.  This especial goes for cuprian and many rarer colors like yellow and cyan without copper.

Bruce

Some Opinions on Nomenclature and Tourmaline

Why do we give things names?   I think that its gives people a economical and convenient way to discuss something as long as both parties have the same thing in mind.  I remember an endless argument with a reasonably intelligent roommate in college that was going nowhere until I actually asked him to define the subject we were talking about.  Well we were not on the same page and when we were things fell into place.   That is why I still call him reasonably intelligent.

In the complex world of color and related chemicals/minerals of the tourmaline group, names and their definitions tend to be multi-level and confusing.   This has come about in part because of the difficulties in chemically or visually determining which chemical/mineral in the tourmaline group you have.  The following statements should be posted in Truth in Tourmaline and I will set it apart so you don’t miss it.

Color alone can not distinguish one species (chemically distinct member of the tourmaline group) from another.

Normal gemological testing can not distinguish between the four species (chemically distinct members of the tourmaline group) that are cut as gemstones, from each other.

Now let us look at some specific examples of multi-level and confusing nomenclature in tourmaline.

DRAVITE

This name for a mineral species in the group of minerals called tourmaline is an old and accepted mineralogical name.  Many tourmalines that are Dravite come with a brownish cast to their color.  But that does not mean that if the tourmaline is brownish, that it is Dravite.  In fact most brownish tourmaline has been determined to be Elbaite, the most common mineral species in gemstones.  The cost of preforming the tests needed to distinguish Dravite from Elbaite were both expensive and even destructive so they weren’t done.  Besides the “look” of the gemstone was the important thing, not its composition.  Still the idea the color could be related to species produced the name dravite as a variety of tourmaline in gemstones.  Dravite, a name that is multi-leveled and confusing.

ELBAITE

The most common color in Elbaite, the mineral species, that is used in gemstones is probably green.   This was certainly truer when Brazil was the more dominant player in the production of tourmaline rough.  Well the gem trade picked up on this and the elbaite, which is still a valid mineral species, became a synonym for green tourmaline.  Other tourmaline color’s that were probably elbaite had their own trade names or were simply called a color and tourmaline (pink tourmaline).   The world of green tourmaline has gotten even more complex with the discovery and exploitation of “chrome” tourmaline another poor choice in nomenclature.  Elbaite, a name that is multi-level and confusing.

CHROME TOURMALINE

The discovery and exploitation of a new type of green tourmaline in East Africa has opened another twist in tourmaline’s nomenclature.   The difficulties in chemically distinguishing  different tourmaline gemstones seemed to have been circumvented by a cleaver filter.  The Chelsea filter exploits the delicate balance between red and green absorption that chrome ions display in gemstones.  It was developed for identifying genuine emeralds from some of its imitations.  In tourmaline, it was found that this new,different kind of tourmaline, that many times demands a better price because of its superior green color, showed a red color that indicated chrome just like in emeralds.   Other tourmaline crystals that did not show the red color in the filter were deemed inferior and continue to be sold at at a discount to chrome tourmaline.  Unfortunately the filter, while showing the tourmaline’s (It turned out to be a Dravite/Uvite the species mixture) chrome content did not show the content of vanadium, which has been shown to be the principle chromophore in chrome tourmaline.  So the combination of the traditional problem of separating different species of tourmaline and a seemingly quick and easy test for the element responsible for the green color, lead to a misleading and confusing bit of creative nomenclature.   This would not have been too bad in and of its self, if it did not help produce a market distinction in green tourmaline.   A distinction that is significant and has no basis in color or any other property of the gemstone outside the ability to show traces of chrome that are not the principle chromophore.

LIDDICOATITE

This relatively recent addition to the tourmaline group is very closely related to elbaite and is found in the same geological setting (pegmatites).  It has been found to exist in areas of a tourmaline crystal that are predominantly elbaite and dominate other crystals,  without effecting color to any degree.  Since color can not separate elbaite and liddicoatite, or any other physical property that can be simply exploited, the trade has focused on the property of liddicoatite from a specific location.  The location is certain pegmatites in Madagascar and frankly no one knows how much of the beautiful banded tourmaline that is found there is liddicoatite or elbaite.  It is both too expensive to determine and really unnecessary.  Still the naming of  banded tourmaline as liddicoatite in the trade is both misleading and does not take in to consideration any examples from other locations as well as Madagascar that are not banded.  (I have a large rose to orangish oval that has been shown by x-ray to be liddicoatite and it doesn’t have any banding).  This to me is another example of multi-level and confusing nomenclature.

PARAIBA, PARAIBA TYPE, PARAIBA LIKE, COPPER BEARING, CUPRIAN, AFRICAN PARAIBA ETC, NAMING FOR THE GLORY OF TOURMALINE.

It is sort of sad that the original name proposed for high quality tourmaline with exceptional colors and a neon like visual impact, from a small deposit in the State of Paraiba, is not included in the list.  I think the name was Heitorite after the man who is most responsible for the discovery of what has become known in the trade as Paraiba tourmaline.  Guided by the need for a “pretty commercial name” for a rapidly rising star from a family of gemstones that has not had a really expensive winner before, the invisible hand of the market picked Paraiba.  It was the first mistake in nomenclature for this truly beautiful gemstone.

To understand why the use of a place name with tourmaline is a fundamental mistake in nomenclature, that transcends Paraiba you have to look at the physical nature of tourmaline and its deposits.   As anyone, that has looked at this site to any degree will see, tourmaline is a highly variable engine of color.  Most, if not all significant locations for the mining of tourmaline,  do not produce anything close to a consistent level of either quality or color in tourmaline.  It also implicitly assumes that the variety of tourmaline named after the location, will never be found anywhere else in the world.  A world full of brief flashes of brilliant tourmaline from locations not yet discovered.

Now let us look at a very brief history of production of Paraiba tourmaline.  There were surface indications of a new and different tourmaline at the site of an old mining claim, but it took years of mining by hand powered tools to make the first significant discovery of tourmaline that is colored by the chromophore Cu+2 (copper in the oxidation state where the atom has given up two electrons.)   During the mining effort to discover and exploit Paraiba tourmaline, significant amounts of tourmaline in dull browns and greens were uncovered.  This material is so unexceptional and without any real value that it would have to be excluded from any trade definition of Paraiba.  The other more important weakness, in declaring the production from this blessed spot on the surface of the earth, unique, is the relatively large  percentage of Paraiba tourmaline from Paraiba that is lower grade in color and quality. This less than top grade Paraiba (maybe even that grade in time) can not be kept separated from paraiba like tourmaline, by eye or normal gemological testing

Two similar deposits of Paraiba tourmaline were found in an adjoining Brazilian state and the trade easily took this in stride.  The material’s grade might not have been as high as the top grade original Paraiba, but prices were going up and the production at the new non Paraiba mines was never that large.  Next came Nigeria and a few waves of doubt emerged about spreading that wonderful name “Paraiba” all the way to Africa.  (Even continental drift was brought forward to show that the African deposit was very close to the Brazilian deposits when it was formed).  Well anyway the Nigerian material turned out to be of generally lower grade (at least in tone level) than the Brazilian and the name Paraiba spread and grew.  Then came Mozambique, with its large amounts of cuprian material in all grades of color and cleanliness and a visual presentation that can challenge the best Paraiba ever produced.  Now I personally have seen very little Paraiba and whether it or Mozambique produces the “best” gemstones is not the gist of this opinion.   My only point here is that Mozambique’s material was causing the name Paraiba to be stretched to the point where the trade had to sit down and make up a definition of Paraiba tourmaline to protect the consumer.

I don’t think the final consensus on defining Paraiba has made anyone happy.  It has focused on chemistry and location, while spreading and legitimizing the use of the name Paraiba for cuprian tourmaline, from any location,in a narrow color range and tone levels.  Now to protect the “value” of the original Paraiba tourmaline, only material from the original deposit with the right properties could be called Paraiba without a qualifier (the two similar Brazilian deposits get a free ticket to ride with Paraiba as usual).  Material from Nigeria and Mozambique that are colored by copper and have properties similar to Paraiba can be called Paraiba type.  Tourmaline within the right color range, likes those from Afghanistan and Pakistan that have the identical colors and tone levels, but not the copper content of Paraiba and paraiba type tourmalines, can be called Paraiba like.  The other colors of copper bearing tourmaline, including greenish yellow and purple, can not be called paraiba in any form and have ended up mostly being called cuprian tourmaline.

Wow, talk about trying to correct past mistakes in nomenclature.  But it is important work considering the buying habits of the consumer and the exceptional heights that the price of this variety of tourmaline has gotten to.  Millions of dollars of effort have been spent in laboratory work to enable the  separation of the different Paraiba’s.  It can be done, but at a significant cost to the consumer.  A cost that may have to be incurred over and over again as the greedy and unethical exploit the public.

There is a weakness in this web of definitions.   It lacks a standard for the visual impact (neon property) of a copper bearing tourmaline in the proper range of tone and color to be called a Paraiba or paraiba like gemstone.  All locations for copper bearing tourmaline produce gemstones with a variety of levels of visual impact for reasons that I don’t believe are well understood.  I have certainly not read about any research on the matter.   The neon property is important in the pricing of tourmaline gemstones and should be seen to be appreciated since it can not be photographed in my opinion.

The complexity of tourmaline has rendered another round of nomenclature both multi level and confusing.

RED, RUBELLITE, BLUE, INDICOLITE, GREEN, VERDELITE ETC.

There seems to a number of people that feel the solution to the problems with nomenclature and tourmaline can all be resolved by distilling the rich broth into, RED tourmaline and BLUE tourmaline and GREEN tourmaline  from Rubellite, Indicolite/Indigolite/Paraiba, Verdelite, Elbaite, Chrome Tourmaline, Cuprian Tourmaline and other established and recognized gem varieties like Achroite and Dravite.  I strongly disagree that simple, broad labels for the maze of beautiful colors in tourmaline can be practical.  In fact I would increase the wealth of names in tourmaline color and support the rigorous application of both the new names and old names when discussing and selling tourmaline.

There is no doubt the proud and historic names like Rubellite and Indicolite have been abused by the trade.  In Rubellite’s case,  various grades of pink and reds that desatureate into brownish gems under artificial light have been labeled Rubellite, when the name should be limited to the best, stable, reddish colors, tourmaline can produce.  With Indicolite, it is natural to want to include blues that are shaded with green since true blue tourmaline especially in a good tone level is a rare bird indeed.   Again Indicolite should be limited to the best, stable blues that tourmaline produces.  With these proud names and other historic names safely defined and supported we have to turn to naming a sea of color in a reasonable fashion.  Great ingenuity and a commercial interest in fine names has produced gems like Canary and Earth Tones for certain colors of tourmaline that are either newly discovered or renamed because of a growing interest in those colors of tourmaline.  I could get into orange and purple etc. which are quite complex colors because more than one chromophore is responsible for the expression of the color, but I will leave this post focused on the more common tourmaline.  This still leaves many shades of varying levels of tone and color without defined names in tourmaline.  Perhaps the best way to progress would be to use pink tourmaline as a guide.  Even with the problem of drawing  a line between pink and red, pink tourmaline is well established both historically and within the industry.   With this model in front of us, well defined names for the following examples, pastel blues (blue tourmaline)and pastel greens (green tourmaline) etc. could be reasonable.

The final piece of my opinion on nomenclature in tourmaline is probably the most controversial.  I would base all my names on color not on chemistry.  If the discerning eye can not see a consistent different in color between different groups of tourmaline as defined by their chemistry, the eye should dominate in naming the tourmaline. (with one name in this case).  I think the roll of chemistry in gemstones should be limited to determining such features as origin, treatments to the gemstone and certainly its natural or artificial nature, not in naming different colors to the confusion of loving eyes and their pocket books.

Bruce

I have been working my way threw the holidays (2013) on a mixture of inter net surfing with some writing and cutting some new pieces of decent rough that I was finally able to get at a significantly higher price then in the recent past.  As I worked hard to keep the table from self destructing on my present effort, a modest round, I remembered an educational post from a very very respected laboratory.  It pictured a fine blue tourmaline of moderate tone as a tourmaline from Tanzania.  My piece is a darker brown orange dravite and a pretty classic example of the type of tourmaline produced from Tanzania outside of chrome tourmaline.  Now,my dealer out of Africa rarely supplies locations for the rough anymore, because the practice of lying about where the rough comes from is rampant.  Owners of the mines don’t want competition to show up at the mine and buy material that has been stolen from him by his miners and artisanial miners have neither legitimate claims or ownership of the places they did their holes.  So now back to a beautiful blue tourmaline with a completely out of place location labeled.  Tanzania has never produced such a tourmaline in my experience and doesn’t not have the appropriate geological setting for the production of gem quality elbaite.  On top of that, Mozambique, a location that could produce such a stone,  has been illegally exporting rough, to circumvent taxes for years and it is right next door to Tanzania.  Mozambique is not the only eligible source of the blue tourmaline either.

So why would a lab with such prestige pick a tourmaline with a suspicious  provenience in an article directed toward the general public?  To show off their collection of superior tourmaline to the world?  They are a non profit organization,  but they do accept donations for their museum. Well, it really makes little difference why they misrepresented the type of tourmaline produced by Tanzania.  To me it represents a complete lack of anything, but a superficial level of knowledge of tourmaline, in the writer.  Now even if they had iron clad proof of a Tanzania provenience, I still think that the stones used in a rather light, fluffy article for the general public, should not mislead people about the world of tourmaline.

TSILAISITE, MANGANESE TOURMALINE, YELLOW ELBAITE.

With all the complaints about the complexity of nomenclature with the tourmaline, I find the level of acceptance of tsilaisite, as a name for manganese tourmaline, to be most exceptional.  Tsilaisite is derived from a region in Madagascar, where yellowish tourmaline was found years ago.  Tsilaisite is only a PROPOSED name because tourmaline with a high enough manganese content has never been found in Madagascan or anywhere else in the world.  There have been exceptional specimens, mostly from East Africa, that have very high levels of manganese and come close to the theoretical level of manganese that is needed to be a different species.  When such a discovery is made (if ever), mineralogy will have to come up with a name for the new species, but gemology already has an accepted name for yellow/orange to brown tourmaline, dravite.

Now I am not saying the I like the name dravite for saturated yellows and oranges that lack a brownish cast, but to use a proposed name for a species of tourmaline that has never been found, for yellow, (most of it is elbaite) is a bit much.  Still people like the name and no matter how many professional mineralogist rally against  its used, I see it defined and discussed often, too often.

Durability of tourmaline in jewelery.  Truth or Opinion?

I have pretty strong feelings about setting tourmaline in jewelery.  I read on the internet over and over again that tourmaline has a hardness between 7 and 7.5 on the mohe’s scale.  That just means that it is relatively harder than quart/sand, which is enough when it comes to durability in gemstones, in my opinion.  Micro particles of sand are ubiquitous in the environment and if a gemstone is not harder than sand, special cleaning procedures (no rubbing the stone) need to be done to keep the edges of the gemstone from abrading.   Now does that mean that all gemstones harder than sand are durable?  The sad answer is no,  some gemstones, including an assortment of tourmaline, can not stand normal physical impacts that lead to chipping even in the normal environment of a well set gemstone.   The two legitimate gemstones that come to mind, that are certainly harder than quart and therefor cannot be scratched by sand, but still chip badly are CZ and zircon.   So where does tourmaline fit into this picture of hard enough gemstones to resist scratching, but prone to chipping.

If you read about tourmaline anywhere on the inter net or in a book, you will generally be told that tourmaline is a gemstone with a very complex chemistry that comes from a usually inadequate list of locations and most every color.  I can’t for the life of me figure out what color is missing from my collection, but few authorities want to included all colors with tourmaline.  Now on top of all the colors and even crystals that multiple colors, one of the principle problem in tourmaline is partially sealed flaws.  Also many of the tourmaline crystals are naturally irradiated in the pegmatite where they crystallized out of the residual from large intrusive bodies of magma.   Tourmalines are also heated to improve their tone level and or color.

Now that I have given a very brief overview of factors that can effect the durability of tourmaline and how vast the world of tourmaline is, it follows the there is a wide variation in the chip resistance and durability of an individual tourmaline gemstone.  Multi color gemstones tend to break where the stress is highest do to the change in color, while dark stones that have been heat to lighten them, tend to be less stable in my opinion.  I would like to say that certain colors like “hot” pink tend to chip more, but I really can not.  You can not tell how brittle a tourmaline gemstone is going to be by its color, but you can loop the stones to see if there are chips on the facets from cutting or any other reason.  I find the keel or culet to be the most sensitive to chipping on the stones that I cut.   If you find chips, the stone maybe weak and not too durable, despite its hardness..

A few more comments on opinions and experiences I have had with jewelry and tourmaline.  I would not put a quality tourmaline in a ring, period, unless it was worn on special occasion to impress the world.  Even with that I would have a protective setting.  Also never use an ultrasonic on a tourmaline,  it may make it, but why take a chance.  Cleaning the gemstone with an old toothbrush (if you need to get into a setting) and rubbing alcohol works fine.  Have your jewelery checked at least once a year to be sure that the prongs are tight.  My goldsmith does not like to set tourmaline and either loosing a stone or having to have it reset is both sad and relatively dangerous.  I have to admit that I do not ware jewelery and keep my babies in display bottles.  If I did have a ring, I would probably buy a high quality synthetic ruby and put it in a gold setting.  With my activities the ruby would be damaged in time and with a synthetic, I would not be destroying a beautiful work of nature.

Bruce

GOLD IN PARAIBA TOURMALINE, NO WAY!

With the advent of modern methods of non destructive/semi non destructive  such as LA_ICP MS (Laser Ablation, Induction Coupled Plasma, Mass Spectrometer) the trace element chemistry of tourmaline has become much more accessible.  Elements such as lead and the rare earth elements are routinely found in cuprian tourmaline (Paraiba like and other colors) but there is one element that has never been found in Paraiba tourmaline, GOLD.  I have both traced the published line of speculation about gold and contacted the German lab that is purported to have found gold at many times the concentration of the earth’s crust.  The lab denies the report and the research papers  are ambiguous to say the least.  On top of that,  many cuprian tourmaline have been analyzed with LA ICP MS and other means to build libraries of data to determine if a cuprian tourmaline came from Brazil of Africa, and gold has never been reported.

I think the reason that the erroneous report of gold in Paraiba has been echoed over and over again on the inter net, is that it may somehow justify the expense of Paraiba and explain its beauty.  Even in the event that gold was discovered in Paraiba,  the chemical nature of gold would preclude it from influencing the tourmaline’s color.

SYNTHETIC TOURMALINE AND COPPER DIFFUSION.

I did not think to write about this earlier because the wave of accusations about both the selling of unreported synthetic tourmaline and its diffusion with copper has about passed.

Tourmaline has been synthesized for years as a tool for science, but I believe it has never been economically produced for the trade.  As most people know that tourmaline is a very complex group of related minerals, you would think that having so many constituents is the principle problem with making tourmaline.  It is not.  Granted the constituents like boron, fluorine, sodium etc. are difficult materials to work with, but it is the rate of formation of tourmaline from the mixture of constituents that really limits the economic production of tourmaline.  There appears to be a kinetic step that nature handles very well, but man does not understand.   The diffusion of copper into tourmaline, that was associated with accusations about flooding the market with synthetic tourmaline has been shown to be technically very difficult if not impossible to do.  It is also a modification to the tourmaline that can easily be detected by analyzing copper isotopes ratios in the treated tourmaline.  I deeply regret that the incorrect interpretation of scientific data lead to the questions about the naturalness and value of tourmaline on the market.  I want nothing to soil the fact that outside of traditional heating, the color of tourmaline is generally not changed by man made treatments.  The principle exception is the radiation of pink tourmaline to enhance its color.  This can  be taken a step farther, by first heating the pink tourmaline with an undesirable over tone to make the stone colorless and irradiating the stone to reestablish a cleaner pink/red.  Each tourmaline has a limit on how dark the pink/red can be made.  It depends, not only on the amount of manganese in the gemstone, but the need to maintain electrical neutrality in the gemstone.  The heating and irradiation of tourmaline is restrained by the possibility of breakage during the process.

Bruce

WHAT IS CUPRIAN TOURMALINE

I have been thinking about this quite a bit lately because of opportunities to sell some stone and the need to price them.  The pricing of top quality gemstones is always a problem because subtle differences between stones can lead to quite a bit of difference in price.  And being responsible in naming a gemstone is important in not deceiving the consumer.

The simplest definition for cuprian tourmaline is tourmaline that contains copper in some amount.   A new species of tourmaline with copper as an essential ingredient has never been found and probably never will be since copper seems to precipitate from the crystallizing tourmaline when the concentration gets too high.   And copper has been found in very low concentrations (trace amounts) in many tourmaline and used by prospectors to discover ore deposits.   So where does that put copper in tourmaline, that meets the gemological criteria to be cuprian tourmaline?  It has to be a chromophore.  A chromophore is an element that is in high enough concentrations to effect the color of the gemstone.  I believe that if copper is a chromophore in a piece of tourmaline, that it meets the “official” criteria to be cuprian tourmaline, but that is not enough to deserve the high prices, I see for the material, in my opinion.

So what is missing from  a tourmaline, which can be of many different colors, that derives at lest part of its color from copper, to make it worth the values put on it?  It is the glow/neon/vivid property of the color/hue.  The hues of cuprian tourmaline are in many cases not unique, especial in the green to blue range of “paraiba type” material from Mozambique because iron can and does produce identical hues.  But nothing out there in tourmaline land can produce the visual impact of a quality cuprian tourmaline.  The “neon” look basically can not be photographed since the attempts I have seen, end up looking like the stones have been over exposed.  I believe the exceptional brightness is generated by the eye/mind, by producing the sensation of the generation of light, not just the reflection of light, in the cuprian tourmaline (This certainly includes Paraiba/paraiba type tourmaline with the right chemistry).  Iron bearing tourmaline such a sea foam and paraiba like hues from Afghanistan can have wonder colors and be very bright, but do not have the visual impact of a quality cuprian tourmaline.

So the bottom line is that without the “glow/neon/vivid” appearance, cuprian tourmaline is not worth the present prices I see it being advertised for.  Many times it is badly included from both its natural load of inclusions and the process of heating.  (I have been told that clarity enhancement is rampant with cuprian tourmaline/paraiba like, etc.)  I do think that cuprian tourmaline has a series of hues in the purples that can stand on their own, with or without the “neon glow”.   The purples formed by copper and a higher oxidation state of manganese can be exceptional and fill in the blue/purple area of the color wheel (along with beautiful shades of reddish purple).  Which is the hardest range of colors in the rainbow for tourmaline to fill.  Every time I examine my large high grade purple tourmaline that I was fortunate to get before copper was discovered in Mozambique, I am moved by its beauty.   Thanks to copper, the world of color in tourmaline has been greatly enhanced, but having copper as a chromophore in tourmaline does not guarantee a valuable and attractive gemstone.

 

Bruce

HOW A POORLY ABSTRACTION EFFORT CAN LEAD TO A POOR DEFINITION OF PARAIBA/PARAIBA TYPE TOURMALINE (A significant subset of cuprian tourmaline).

I am back at it again, reading the inter net about tourmaline.  I just reread the classic research paper by Dr. Rossman and company * while focusing on why some Paraiba/paraiba type tourmaline are green.  The currant definition of Paraiba/paraiba type, gemstones only includes copper and manganese as significant chromophores in their make up.  The paper’s abstract does not include a statement about any other chromophores, but if you read more, it becomes obvious that manganese in either of its oxidation states or copper in its plus two oxidation state can NOT produce a green in tourmaline alone.  (More or less copper does not make a greener or bluer blue.)

At first the paper says that analysis found very little vanadium, chrome, iron or titanium in the tourmaline from Brazil with a high concentration of copper (Paraiba).  But then it says that the gemstones with HIGHER levels of titanium absorb more light in the purple blue end and produce a greener tourmaline when it works with the principle absorption peak of manganese plus three and copper plus two peaks.  The form of the titanium that is a significant chromophore in at least some greenish tourmaline is a charge coupled transfer reaction,  Titanium plus four and Manganese plus two.

Why the definition for Paraiba/paraiba like tourmaline  does not include titanium in the essential list of chromophores for at least some greener cuprian tourmaline (some greener tourmaline from Mozambique has been found to contain significant amounts of Iron, independent from Titanium.) is beyond me.  The abstract is certainly not very long and the exclusion of titanium certainly could have lead to the present definition of Paraiba/paraiba type tourmaline that is at least incomplete if not fallacious.  (You can have Paraiba tourmaline without any significant contribution from Manganese or Titanium as a chromophore.  In fact the production of cyan blue Paraiba and paraiba like tourmaline by heating has the aim of getting rid of purplish and greenish tones produced by Manganese and Titanium.

As I have written, the weakness in the definition of Paraiba etc. is much more profound than the lack of completeness in its chromophores,  because it is based on chemistry and not on the discernible gemological traits of the tourmaline.  In other words the “neon/electric etc.” glow that should be present in any tourmaline that is blessed with the label cuprian/Paraiba/Paraiba type) tourmaline is not included in the definition.  Yes, they do talk about, brightnes and tone value, but the definition never fully addresses the most important property of Paraiba/paraiba like tourmaline outside of its color, the glow.

 

 

 

 

 

 

 

 

 

 

 

 

 

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