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Andesine the Facts

Discussion in 'Colored Stones' started by PhilipL, Jul 25, 2008.

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  1. PhilipL

    Jul 25, 2008
    by PhilipL » Jul 25, 2008
    Hello to all. I wanted to share this information that was presented to me this week. I am a student of the ISG (International School of Gemology). I am sorry however that the pictures did not come out. But I would recommend that you go to the site and see for yourself. I do hope this will let people know what has been happening with the so called Andesine.

    23 July 2008
    ISG report on the diffusion treatment of andesine! How could this scheme exist in the gem trade industry for over 6 years? I take no pleasure in issuing the following gemological report on our investigations of the so-called “andesine labradorite” that has been sold on the market since 2002. For while the Raman scans and microphotographs all speak to the fact that this material has been artificially treated to induce color, they also speak to the fact that some people in the colored gemstone industry have at best been negligent in their responsibility to consumers, and at worst may have perpetrated a criminal fraud against consumers. In previous reports published in various venues we have produced evidence to prove that none of this “andesine labradorite” reported to come from the Congo, Tibet, Mongolia, and who knows where else in China, is even close to being equal gemologically to the Oregon Sunstone Labradorite. We have demonstrated that the gemological properties are significantly different, that the “andesine labradorite” red and green colors show significant signs of having been artificially induced, including the fact that the material starts out as yellow feldspar. Recently, virtually all of the dealers of this “andesine labradorite” material have changed their original story that all of the material is totally natural and untreated. Now, most are claiming that the material starts out as yellow labradorite and is heated only to turn the red and green colors. Even a video by Jewelry Television of the claimed Mongolian mine showed the rough coming out as yellow. But there is one important question that we have put forth to the “andesine labradorite” dealers that none has been able to answer: Question: How do you turn iron based yellow feldspar into copper based red and green andesine by nothing more than heating the stone? Since not one “andesine labradorite” dealer seems to have a clue about the true nature of their product, we decided to start buying specimens for testing. We first asked the three biggest producers of the Oregon Sunstone Labradorite mine owners to send us rough from their mines for use in testing and comparison of the “andesine labradorite” being sold by the Chinese. Then, we purchased specific specimens from every dealer of “andesine labradorite” that we could find including Jewelry Television, Direct Shopping Network, eBay,, and anywhere else we could find sellers hawking this material. We collected over 100 specimens. You can see the collection in the photograph below. The gemstone box papers are full of over 50 individual specimens, with the balance left in their original boxes and containers as used by the sellers.

    As most people may know, the ISG recently obtained an Enwave Optronics Raman Microscope through the efforts of a lot of consumers and ISG students and graduates, as well as the ISG office. We put this new technology to good use by producing a lot of important information that only this level of technology could provide. We added our own microphotograph capabilities, and a little bit of just plain old gemological common sense to come up with the final version of this story. It is not the complete version as we produced literally hundreds of photographs and performed over 800 Raman scans to obtain the following information. But below is the answer to our question: How do you turn iron based yellow feldspar into copper based red and green “andesine labradorite” by nothing more than heating the stone?
    Our first order of business was trying to establish if there are, indeed, numerous sources of this material. For just as we found with other gemstones, if there are different sources for red and green “andesine labradorite” then those sources should produce variable Raman scans.
    Unfortunately, that did not happen. We have a known specimen of Mexican yellow feldspar in our office. When we ran scan after scan through the Raman Microscope of andesine specimen after andesine specimen, all of it proved to be…..well, Mexican feldspar. Below is a composite of the Raman scans we did of a cross section of our specimens from all reported sources. You can see that all of the scans are virtually identical to the Mexican yellow, which tends to prove a report we had earlier that over 30,000 kilos of Mexican yellow feldspar was sold to the Chinese just a few years ago. The Mexican yellow feldspar Raman scan is in black.

    We even have a couple of specimens of the 2008 Olympic Andesine from DSN to test out. Below is their Raman scan. You can see the Mexican yellow feldspar as the black line and the DSN 2008 Olympic andesine in blue.

    The next step involved what we at the ISG office call the Old Geezer Rule. The Old Geezer Rule says that anyone in the business a long time will usually be able to spot something wrong in a gemstone out of sheer force of the number of gemstones that the Old Geezer has looked at over the years. It did not fail us here.
    Below you see a panel of gemstone images taken through an immersion cell. All of these are red or green “andesine labradorite” showing a feature that we started seeing in scores of our specimens. Now we know that the Oregon sunstone can have green and red splotches in the rough and finished. But what are the odds that all, 100%, of the “andesine labradorite” specimens showing this feature would have a green core center and a red outer section? The panel of images you see is simply what we had room to put in. We could cover page after page with these from our specimens, and all with exactly the same color pattern, in the same order, and in the same positioning.

    This exact same identical feature in so many specimens is enough to make the Old Geezer in me totally convinced that this “andesine labradorite” is being diffusion treated without any further evidence. But there is more. Oh boy, there is more!
    Since we know the material is virtually all the same, and most shows a significantly unnatural looking internal formation, we wanted to look even closer to see if we could find the smoking gun. We wanted to find the actual filler material being used to artificially induce this red and green color into this otherwise yellow feldspar.
    We found it.
    It is the nature of plagioclase feldspars to have a lot of twinning, that is when the crystal grows and doubles on itself creating what is called lamella by some scientists, but we like to call them ribbons. In literally 100% of the specimens we observed, whether from Congo, Tibet, Mongolia, China, India, Mexico or anywhere, all of the feldspar showed these ribbons. Here is an image to demonstrate:

    For the most part these ribbons are oriented parallel to each other, and are fairly uniform in shape and color as you can see above. But these ribbons do reach the surface of the rough crystal. From previous reports we also know that the diffusion treatment of “andesine labradorite” is done on the rough feldspar, which means that if we could find some specimens where the ribbons in a cut specimen were close to the outer edge of the rough during treatment, we might be able to actually find the diffusion material and totally prove the issue.
    Having been in this business for 37 years, I know that with any gemstone treatment there are always screw ups. Treated stones that did not come out like the “cooker” wanted are discarded. It is usually the screw up stones that give the best examples of telling how the treatment was done. Eventually, some poor dealer is going to offer the “cooker” a few baht for the box of screw ups, and……sell them on eBay.
    Again the Old Geezer Rule paid off.
    On any given day we could find close to a thousand “andesine labradorite” gemstones for sale on eBay. Due to the Thai dealers taking very good images for their auctions, we could find those screwed up diffused “andesine labradorite” gemstones by the excellent images in the auctions, and “Buy It Now” as eBay says. By the scores did we buy them. Sure enough, we found the smoking gun; actually several of them, the diffusion treated “andesine labradorite” gemstones that were so screwed up that any logical dealer would have buried them in order to make the identification of this process as difficult as possible. But greed usually wins out over common sense. And it did here also. The Thai dealers sold us the very specimens of diffusion treated “andesine labradorite” that we needed to prove the case.
    Feldspar ribbons are weak points in the crystal structure. Sort of like little tubes running into the stones. When these feldspar ribbons are exposed on the surface of the feldspar rough being treated, the diffusion material is forced down these ribbons at a rate that is higher than the surrounding material. This leaves a ribbon that is no longer flat and translucent, but one that is filled with diffusion material that becomes translucent to opaque, as shown below:

    This ribbon was at the surface not only of this faceted “andesine labradorite” but also of the rough crystal during the diffusion treatment. You can see how the ribbon was filled with foreign material that is nowhere near like anything naturally found in a feldspar ribbon (or lamella for your science guys).
    Over the course of inspecting scores of specimens, we found literally hundreds of these ribbons that had been close to the surface of the rough during treatment, and were filled with diffusion material. As an example, we are going to look at three specimens. Below is a red “andesine” supposedly from the Congo. Notice how the coloring is either faded or lost along the planes of the ribbons. This was found in many specimens because when the ribbons broke the surface of the rough they tended to suck up the diffusion material, leaving the surrounding area of the gemstone colorless. You may have one at home and you can see this for yourself.

    But if you look at the stone where the ribbons end at the surface, and also ended at the surface of the rough, something strange is visible. The diffusion material becomes very visible in higher magnification. Below you see many of the ribbon lamella from the andesine above showing how the diffusion filler material has filled a significant section of the ribbon.

    In the image below, we have yet another example. This is a huge ribbon that has been totally distended by the filler material which is showing a white powder that has filled this ribbon from one end of the stone to the other.

    In the high magnification image below, you can see up close the material that has caused all of this confusion and grief over “andesine labradorite”.

    Late one night while running Raman scan after Raman scan, and taking microphotograph after microphotograph, we found it. We found that specimen that the Thai or Chinese “cooker” should have thrown away, but didn’t. And we got it.
    Below you see what appears to be a lightly included red andesine. But at the left you can see a dark area. This is a huge ribbon that breaks the surface of this stone. After seeing this feature I put it into an immersion cell to see what was really going on.

    In the immersion cell I could quickly match this andesine to that panel of andesine above that showed the green core and red outer areas.

    Zooming in on the stone with my Meiji Techno microscope on 30x, I could quickly see that we had something special here. We had the red diffusion filler material still intact, and still showing the artificial red color is imparted to this feldspar. You can even see how the color was diffusing into the otherwise yellow stone around the ribbon area.

    I took this stone out of the immersion cell and kicked up the magnification to 60x and found the diffusion filled ribbon to show exactly the same effect in air.

    Finally, at 90x, the story of the “andesine labradorite” was finally ended. This material is all diffusion treated to impart the red and green color. This gemstone shows the proverbial smoking gun. In the image below, you see the red diffusion material still stuck in the ribbon that never made it into the interior of the gemstone. Proof positive that this “andesine labradorite” claimed to be untreated and from the Congo, is actually diffusion treated yellow feldspar from Mexico that stopped off in China or Thailand and was supposed to have been on its way to a local US jewelry shopping channel.

    Unfortunately, the diffusion treatment did not take very well with this stone, and it ended up on eBay rather than Jewelry Television or Direct Shopping Network.
    Normally at this point I would breathe a sign of relief at having finally found the answer. But as I post up this final image, I realize that this image means that thousands of consumers have been defrauded of millions of dollars by this scheme. This is why I opened this report with the fact that I take no pleasure in writing it. I am glad to finally have an answer for consumers, but I regret that the answer means that someone somewhere is guilty of misrepresentation and potentially of criminal fraud.
    Where this goes from here is outside of the realm of my office. But I hope that consumers will get their day in court. I know I will be there with my information.
    But even more, I hope that those in the industry, both who perpetrated this fraud and those who turned a blind eye to allow it to continue, get what’s coming to them. Someone is going to have to pay for this being allowed to happen for 6 years without something being done, and I hope that justice is swift and severe.
    To the consumers, I promised you that we would all work together to get you an answer and now you have it. My hat is off to all of you because it was you, the consumers, not the gemstone industry, who got this answer. I am not sure that the gemstone industry understands just how dire of a situation they are in over this “andesine labradorite” issue, but I assure all of you that the International School of Gemology will never allow this to happen as long as we are standing our watch alongside all of you. That is our promise to each and every one of you.
    Robert James FGA, GG
    President, International School of Gemology

    A SPECIAL THANK YOU: The ISG is preparing a special Hall of Honor Section in the ISG and YourGemologist for all of the good people who helped us obtain the Raman Microscope from Enwave Optronics which made this study possible. Without each one of you this would not have been possible. RJ
    ©2008 International School of Gemology . We urge and support sharing of this information in its entirety, with copyright notices intact, to others who are interested in the study of gemology. Jeweler’s Associations are welcome to distribute to your members.

    Visit the ISG Website Contact the ISG Take a 10 minute video tour of the International School of Gemology
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