a 501(c)3 Non-Profit Education Organization
9 May 2017
ISG Magnetism and Gem Identification
This is real science, not voodoo science...
It was quite an amazing revelation when I first heard of Sylvia Gumpesberger's work on gemstone magnetism. Sylvia is one of those gemology pioneers who open up new horizons in gemology, and then drag the rest of the industry kicking and screaming into new concepts and new technology. The following year I was honored to have Dr. Don Hoover visit our booth at the AGTA Gemfair in Tucson where he demonstrated the separation of garnets based on magnetism. When you think about it, the iron content of many gemstones is sufficient to create a magnetic attraction, and this was the basis for the reports.
But....there was more to come than most realized. By applying the very real science of gemstone magnetism the ISG was able to expose some very creative gemstone cookers who were trying to use voodoo science to increase their ill-gained rewards from undisclosed treatments. Here is how we used this on one example.
Having worked with Jules R. Sauer of Amsterdam Sauer, one of the largest gemstone mining and production companies in Brazil, I had collected a variety of pink tourmalines direct from the mines through Amsterdam Sauer, three of these can be seen at left. So when I started seeing very intense pink tourmalines show up in the market at very cheap prices and all perfectly matched, the sirens went off in my head. (the warning sirens, not Scylla and Charybdis from Greek mythology). Given that the ISG office knew that many of the treatments on tourmalines were using different forms of iron and manganese, I decided to set up a comparison test of magnetism in tourmaline just to see what we could find. The results were profound.
There are a couple of methods to test magnetism in your kitchen, one of which is place the stone on a float in a bowl of water and pull it along in the water. I demonstrated this in our 2007 YouTube video on Gemstone Identification Using Magnetism. I have used this method in other demonstrations, but for this time I found that the set up below is better for this purpose. By suspending a copper wire holder on a long string, with a series of lines on the bottom paper, I could photograph the magnetic attraction to the best advantage. The lines do not mean anything in particular other than simply showing the amount of movement. Below is a natural pink tourmaline from Amsterdam Sauer, Sao Paulo, Brazil.
Notice that with a natural pink tourmaline the movement is slight. I allowed the pink tourmaline to get very still, then simply placed the magnet to the side of the stone and tried to pull it by magnetism away from the center point and see how many lines we could move the stone. This image demonstrates natural pink tourmaline.
I next demonstrated with a suspected treated pink tourmaline and the results were profoundly different. By placing the stone in the holder, and moving the magnet toward the stone and pulling back, I could get the stone to move a significant distance, far beyond the reported normal reaction for tourmaline magnetism.
This was an amazing magnetic reaction to a gemstone that was supposed to be only slight to moderate in reaction. I referred to an outstanding expert on gemstone magnetism, Kirk Feral and his website: Magnetism in Gemstones to further confirm this information and found that the darker pink tourmalines should normally be less susceptible to magnetism, but in this case I found extremely strong attraction to the magnet by these unusual dark pink tourmalines. But to make sure I was not picking something up from the faceting process, I next used rough crystals that had not been worked. First, the natural pink tourmaline crystal from Amsterdam Sauer.
Once again, with this dark pink natural tourmaline we got very limited response to my magnet. It was approximately the same level of response that I got from our known natural faceted pink tourmaline. So I moved to a suspected treated tourmaline obtained on the market.
As predicted and repeated in several stones, the pink tourmaline rough crystals that demonstrated signs of artificial treatments were strongly attracted to the magnet. I used an industrial level magnet for these tests to get clear results.
And just for good measure, I offer yet another of the pink tourmalines from that demonstrates the exceptionally strong magnetic attraction through this demonstration.
The question was, however, how do I prove that something has been done to these tourmalines by gemstone cookers?
To get this answer I turned to an independent scientific lab, Evans Analytical Group for LA-ICP-MS testing of a variety of tourmalines. The results were once again...profound. Iron (Fe) and manganese (Mn) are normally trace elements in tourmalines that cause the various colors. I had both faceted and crystals, pink and green tourmalines tested, two of the results are below. There were two issues that quickly came to light:
The presence of Fe and Mn was extremely high, well above what would normally be expected for natural, untreated tourmalines.
Based on research reports from the GIA, the lead (Pb) levels confirmed that we had tourmalines from different mine locations, the one common factor was that all of the tourmalines showing anomalous Mn and Fe levels came from dealers in one country known for gemstone treatments.
Below are two of the actual LA-ICP-MS reports from EAG Labs, and to better demonstrate the unusual amounts of Mn and Fe in these stones, I show a bar graph for comparison.
From our 2013 report, the graph at left shows you the relative levels of Mn and Fe of the treated tourmalines (in red and green) to what would be the normal elemental make-up shown in blue.
Two of the LA-ICP-MS reports from EAG Labs. "Matrix" denotes extremely high levels of the elements, above the reading scale.
While the unusually strong magnetism did not diagnostically prove that something was amiss with these tourmalines, it did serve as an important "tell" that something was wrong. By LA-ICP-MS testing I showed that indeed, someone is artificially infusing color elements into these stones which is clearly demonstrated by the EAG Labs independent testing. But by using a simple magnet, we can identify at least some of these without the cost of the advanced testing. Thereby proving the importance of magnetism in gemology.
The use of magnetism is an ongoing study with much yet to be learned and applied. There are many out there doing excellent research and we look forward to the future results of that work. For now, we applaud the work of Sylvia Gumpesberger, Don Hoover, Bear Williams and Kirk Feral, along with several of our own ISG Community. We applaud everyone for your excellent work and look forward to even more important news about this unique gemstone property that is now coming into its own merit.
Robert James FGA, GG
International School of Gemology Inc.
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See our YouTube video on Gem Identification Using Magnetism
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