The Definitive Guide to the World of Color in Tourmaline Gemstones

The Definitive Guide to the World of Color in Tourmaline Gemstones

Search and research, an on going adventure.

Posted by: The Bruce Fry Tourmaline Collection

June 2, 2021

I have had an interest in rocks and minerals for as long as I can remember, but I really did not get into tourmaline until I started faceting at the age of fifteen. My parents had gotten me a big chemistry set for Christmas and my mother had concerns. I was having too much fun doing things with the chemicals that were not in the book. I am sure that she feared that I would either hurt myself or at least burn the house down or both. She instructed my father, a researcher at the Bell Labs to find me a new hobby to keep me busy in the basement. Drawing on his acquaintances and voyages of discovery, I tried painting porcelain and other creative projects until I went to see an old boss of his. Stewart had many interests, but little time to pursue them. But with his help we found the hidden world of lapidary spread out threw Northern New Jersey. So at thirteen I began to cut cabochons on an assortment of old industrial equipment and new lapidary equipment. I still vividly remember the first translucent green nephrite cab that I cut from material given to me by Stewart. It certainly wasn’t perfect, but it still shown with beauty. I cut cabs for a couple of years and then faceting beckoned.

We lived only about thirty miles from the home of the inventor of the basic platform style faceter that I still use today. Shaw had a strong following in the area and Stewart had one, so that was what I wanted. It took every cent that I had saved in my bank account to get the simple basic set of laps and machine and then I was only able to get my mother to let me spend the money, after I took lessons from an active cutter and Shaw. After a couple of wonderful lessons learning to facet, I was hooked. I didn’t have any money for rough, but a local dealer let me cut some pieces to demonstrate the quality of some of his rough (He also paid me in rough) and Steward step up his support by giving me some beautiful rough. I think the gemstone that finally really sold me on tourmaline was a fine piece of Rubellite from Madagascar. It was the finest gift that Steward ever gave me and along with the other colors of tourmaline, I was able to help satisfy my need for color in my life. As the years have unfolded I have tried many hobbies (woodworking, needlepoint, ceramic) and color is always an important factor, but the colors of tourmaline have always kept my interest in lapidary alive. (I also like agate, but that is a different story.)

I continued to cut a very limited number of gemstone threw most of college and then the lapidary fell silent until 1998. I was single again and working for a needlepoint shop, making elaborate pieces when a friend at work (I was an engineer for the Commonwealth of Pennsylvania for most of my career) wanted a gemstone ring for his wife. We talked about it and I found my old machine and search that new invention the inter net for material. The fires were reignited and I soon realized that the only way I would quench them is to cut my own gemstones.
I had to buy a new set up because the old one was very limited (rounds and eight/four sided gemstones) since I had never upgraded it. With this new outlet for my creative needs, I dropped working for the needlepoint shop and tried to buy decent faceting rough. That turned out to be quit a learning experience until I found a few dealers that I could reasonable trust. I continued to cut a variety of materials, but only tourmaline could reasonably give me the variety of color boosts I needed. And so I decided to do two things, develop the best polishing method for tourmaline that I could and go for everything in tourmaline color, from the just plain ugly to ambrosia. Fortunately a window of beauty was opening up in tourmaline from Mozambique in the early years of the new millennium and my quest for the widest expression of color in tourmaline put me in the right position to benefit from it.

I have an Extractive Metallurgical Engineering Degree and chemistry has always been a significant interest in my life. So as I cut and collected my colorful collection of tourmaline, I tried to find out about the chemistry of tourmaline color. I mourned in not being able to get a blue/purple from Brazil, since basically all cuttable examples of that color have been heated to make cyan Paraiba. I was much more successful in getting tourmalines with an orange tone, now that Africa has come into its own. And so the quest for color in tourmaline continued, but when I looked at the work on color in tourmaline, it was neither inclusive nor even consistent at times. In the beginning I never felt that I would have something in tourmaline that had never been seen before by science and spend years trying to have research done on it. And then “Laurellite” entered my life.

Laurellite is a name I gave to cuprian tourmaline, that demonstrates a reverse Alexandrite color change from violetish in natural light to a slightly greenish blue in incandescent light. As far as I know, it has only been found in Mozambique, but since this shade of color in tourmaline is usually cuprian and therefor can be heated to the much more valuable cyan color, the few examples of Laurellite from other locations have probably been heated.

The first first piece of rough in my life that would become Laurellite did not look that promising. It popped up on dealers web site out of South Africa and did not have a great deal of eye appear. It had been heavily ground and looked rather gray. And though it mentioned blue/purple I did not jump on it. It was still early in the collection game, just after the millennium and I had just finished cutting a large tourmaline crystal that was supposed to be blue purple and turned out to be gray. (It was a nice gray so it was not a complete lose.) Still the dealer, one of my principle ones, knows my weaknesses and emailed me about the rough. He had a good story, he and a miner (really an independent traveling wholesale buyer of rough from the mines) had looked threw a pouch of different, less valuable, but still interesting rough that the miner carries with him. The dealer immediately recognized the rough in question as a tourmaline, while the miner had thought it was an iolite. Well, the rough was different, not that expensive and came with a personal invitation, so the “Laurellite” adventure began.

Upon recite of the rough, my interest was again deflated. The well ground crystal had what I call radiation burns on parts of its original surface, that develop from Mn+2 being oxidized to Mn+3 (a reddish plume is still extent in the finished gemstone.) and a number of feathers. As I ground out the feathers, I could see no violetish hue. (It was winter and I was working under an incandescent light.) But you never really know what color you have in tourmaline until you get it off the dop stick and see it under different lights. So the work went on into the dark winter nights and the finished stone still appeared gray, as I prepared to take it for a walk in the weak winter light the following day. You can imagine my surprise when the stone turned violetish as I opened my front door. Now I didn’t completely trust my eyes because I had never heard of such a color change, violet in natural light and blue gray in incandescent , in any gemstone, let alone tourmaline. I therefor set out to test, seeing the color change, with innocent people and they consistently saw the the color change, with pleasure I might add. Now this went on for over a year and then the big bang hit.

My main dealer out of Africa sent me an email that said he had a piece of blue purple tourmaline rough for me. He did not send a picture or even mention the size or quality of the rough, but I knew I had to have it. I immediately emailed back that he should included it with some other tourmalines I had order. When I opened the well sealed shipping evelope in my dinning room, that was a nice sunny place that day, I was ecstatic to see a moderately sized blue purple piece of tourmaline rough smiling up at me. I did not have to see the piece under exceptional lighting conditions to know it had a good tone level and a clean demeanor. I was laughing and bouncing off the walls so much that I am fortunate, that the neighbors don’t have any windows that really face my dinning room. When I calm down from just seeing my first truly blue/purple tourmaline (The first Laurellite was only a violet in natural light) I immediately set out to cut the rough. The rough was very clean and did not appear to be dichroic. The pebble was water worn, but did have some indications of crystal structure remaining on it. I did not concern myself with orienting the rough and I am not sure where the c axis is to this day. After I finished the emerald cut that went quite smoothly, I settled down to enjoy its beauty under different lights. And low and behold it was a reverse Alexandrite color changer. Its change from a violet in nature light to a blue with a touch of green in incandescent light is the highest quality change that I have. (why I saw blue and not just purple in the tourmaline the first day probably came from reflected light in the room that had become redder than pure natural light during the middle of the day) With this stone I had the confirmation that the first Laurellite was not just a fluke and I needed to have research done on the Laurellites to understand and present this material to the world. Or at least a few tourmaline addicts. But how to do it.

I had been dealing with a web site out of California call “roughtocut” and getting some great Afghanistan tourmaline rough. I also knew that they had donated to the GIA and were generally known to them. I myself was a no buddy and I had the strong feeling that if I sent in a tourmaline to be evaluated, I would get back that it was blue purple, its weight and size and that it was a tourmaline. In other words, the standard evaluation that would probably never notice the color change feature. (In fact the certificate I did finally receive for the original stone I had sent in, does not mention the color change property.) Color change is a property that needs the proper conditions to be evaluated.

I discussed my dilemma with my principle contact at rough to cut and he agreed to try and contact a researcher in GIA to alert them that something exception was going to be sent it (he ended up sending it in). I just knew that if I asked for a contact and was told no that would be the end of my effort. Well my contact was able to be patched threw to the library and arranged a reception for the color changer that I did no know contained copper or even meet the GIA’s stringent requirements to be a color changer.

I was very exciting to hear back on my birthday that the material I sent were strong color changers (this I actually learned earlier than my birthday) and contained copper as a chromophore. I was asked to edit the proposed article for their Gems and Gemology magazine and sworn to not reveal the contents of the article until it was published. I knew that the copper part of the news, which I did not expect, would be really a big event for tourmaline and Mozambique, and it was. A second follow up article in Gems and Gemology focused on a quantitative analysis of the tourmalines and declared the tourmaline a new variety of Elbaite. It also stated that a complete colorimetric study of the reverse color changer would answers about why the tourmaline changed color.

The research and writing of the articles had taken over 2 years, but I was on a roll. I contacted The Gemological Laboratory of All Japan and had the color changers (now Laurellite to me) tested with a LA-ICP-MS instrument. I found out that the Laurellites contained about 3 times the amount of copper that was found by the GIA. I contacted an expert that had worked for the GIA and had a colorimetric study done on Laurellite that resulted in the publishing of an article in the British Journal of Gemmology. I even found a researcher that showed me that the produced by passing day light threw a sheet of primary yellow color could cause Laurellite to change color. Now all of this was great, and I never expected to be instrumental in finding a new source of cuprian Elbaite or a new variety of Elbaite, but I have been unable to get serious research done on the physical reasons for Laurellite’s difference, from tourmaline with a similar chemistry. The discovery, that the Laurellites, I have been able to have analyze, have hundreds of ppm of lead and a significant amount of barium, both of which can be the final products of radioactive, leads me to believe that the distortion of the unit cell by alpha radiation could be a factor in Laurellite.

In the following paragraph or so I just want to give you a sense of my frustration with trying to have more research on Laurellite and cuprian tourmaline general.
I traveled to New :York City so that an assortment of cuprian tourmaline including Laurellite could be examined and tested with a LA-ICP-MS. It took two years to get the stones back and the laboratory refused to release the data to me in the end. I was dropped with anger by a college professor, who is an expert in spectrometer, after asking if I could have my name put on a paper he was working on, if I helped buy a new spectrometer, supplied stones and did some data analysis. I have been lead on by a professor that needed a project for a student to use an electron microscope and then has failed to do any research with Laurellite or even keep possession of the irreplaceable samples. While, earlier, I had a laboratory drop their interest in Laurellite because I was unable to get samples to destroy. I tried to get unit cell dimensions for Laurellite and was told to save my money for reasons that were not cogent to my effort. I have sent many emails to institutions that offer their services to both in house groups and the public without even a reply. That is not all, but I think that this gives you a general idea of how an unknown person without credentials is treated by at least some of the research community.

But the quest for understanding of color in tourmaline continues with my purchase of a modern spectrometer and light source. Everything went very smoothly with testing my collection for copper except for the interference of Mn+3 (which causes a red tone in tourmaline). Mn+3 can sometimes mimic a copper peak in the infrared and my spectrometer does not have a broad enough range of wavelengths to distinguish Mn+3 from Cu+2. I also discovered that the recommended light source for my spectrometer does not have enough of the blue end of the spectrum to produce a good absorption curve over the full range of the instrument with many stones. This was not a problem with looking for copper since the pertinent absorption peaks for copper are at the red end of the spectrum, but it precludes getting an accurate appraisal of the broad range of tourmaline colors. I have since purchases a xenon light source that has had its own problems along with a breakdown in the spectrometer. I have since had the spectrometer repaired and upgraded and I hope to get data later this summer (2014) with a well calibrated system of the spectrometer, an integrating sphere and the xenon light source.

I have been posting some information on Laurellite research, but it is time to report on this page. During the summer of 2017 I visited the GIA laboratory in Carslbad CA. We discussed research and I left two specimens of Laurellite. They have been accurately oriented and ground into squares. This inabled the lab to measure carefully the color of the Laurellite on its axis. The pieces were the heated to reduce the manganese +3 oxidation state to manganese +2 which made the stones blue. Their color was measured again. The included samples were so completly damaged by the heat treatment that it was difficult to measure after heat treat. The rough I gave the lab did not have flaws and feathers, but its crystal was not good due to a world of small inclusions. It was also a rather grayed color.

About 6 months ago I finally resolved my spectrometer problems. I returned it to the manufacture because I faced the fact that I could not resolve the lack of its sensitivity problem, after I had it up graded. It turned out that the instrument had not had its gain properly set at the factory. A simple readjustment of the resistance (pot) on the gain cicuit was nothing to do and they did not even charge me for the adjustment. I improve the performance of the blue end, by having a filter installed on my tungsten light source. It has definitely helped with better absorption curves. (I have not tried the zeon light source on this set up and since it is filtered it probably will not work better.) The only other upgrade was the use of a stand for the glass fiber probe.

I have now generated new absorption curves for most of the interesting tourmalines in my collection. I did find copper in some of the new tourmaline, but there is not too much copper bearing left out there on the market. I will be writting more about the specifics of using my spectrometer and tourmaline in sporatic posts.