Is UNA Destined to Become The New Emerald City?
Jan. 9, 2015
Bryan Rachal, Public Affairs and Media Relations
FLORENCE, Ala. – On a recent food show, the host tried to sell random people a pizza for a higher than normal price by simply listing the ingredients. Not surprisingly, few were interested in paying more. The host then tried to sell the same pizza for a higher price, but instead of just listing the ingredients he described how they were made and the source of the ingredients. For example, the tomatoes were heirlooms from a small village in Italy and the Mozzarella was specially made from buffalo and smoked. You don’t have to be a genius to figure out the point of the piece; people were willing to pay more for the pizza with sourced ingredients. In fact, that’s the current trend; people want to know where their “stuff” comes from, whether it’s food, coffee or textiles, it’s important and apparently people are willing to pay more for it.
That same logic can be applied to the gem trade. Emeralds, rubies and diamonds all fetch a hefty price off name alone. But what if I could tell you exactly where your emerald came from and what type of rock was involved, would you pay more? Well yes, according to Dr. Brian Thompson. Thompson currently serves as a professor of physics at the University of North Alabama and his specialty is light and optics. Now, you’re probably wondering what that has to do with gems and you’d be right, it really doesn’t apply to all gems yet, but it does apply to…emeralds.
As mentioned, Thompson specializes in light and optics, but more specifically he deals with the interaction of light with matter, which is a very important key to his recent research. But before we can learn about his latest research with emeralds, we need to know what led up to that point. Thompson said it was an initial project dealing with fluorescence.
“I had just finished up a project where I had been studying fluorescence effects in microscopic particles,” Thompson said. “Fluorescence is the conversion of a high energy light to a low energy light by a material so it looks like it glows. Like a black light, if you shine a black light on fluorescent paint and it glows, that’s because the ultra violet high energy light is being converted into a low energy light that we can see because of the paint.”
Thompson said certain gemstone materials or rather different minerals work the same way when you point a high energy light at them. Thompson said the energy of visible light is matched to the rainbow of colors that goes from red to violet, with violet being a high energy light and red being low energy on the visible spectrum that humans can see.
“So you can shine, for example, violet, blue, or green light on different minerals and see them glow red. This is something that you can do with emerald. It’s one of these materials, if you have a bright enough light source and you shine that light on them, they’ll glow red. Of course emeralds look green under normal lighting, but if you shine enough high energy light on them they’ll definitely glow red,” he said.
The reason why this is possible in the first place is because emeralds’ green color arises from the presence of chromium, and this chromium in emeralds can also fluoresce. So it is this fluorescence from chromium that the spectrometer picks up and measures.
Now it’s important to point out that emeralds can be made synthetically, and, of course, they’re also found naturally. Thompson said that the problem lies in the fact that synthetic and natural emeralds are difficult to distinguish between the two because of the fact that they’re chemically the same.
“They’re the same material. The synthetics are the same chemistry as the naturals, so when people buy an emerald, the natural emeralds are going to command a higher price. But how do you determine if you have a natural or a synthetic emerald? So that’s kind of where we were starting from when we started this work; maybe we can add to the number of known methods that are used to distinguish between natural and synthetic emeralds,” Thompson said.
Using a green laser, Thompson found that all emeralds, synthetic or natural, will glow red if you shine a bright enough light on them. As mentioned above, in laymen’s terms, a spectrum is basically a rainbow of colors that we can see. Getting more scientific, a spectrum is the brightness of different colors, as seen in a rainbow, produced by dispersing the colors of light according to their different energies.
“So when we take a fluorescence spectrum of emerald, what the spectrometer spits out is basically a curve composed of two bright lines in the red color range. Then we measure the energies at which these lines peak” Thompson said.
Using that as a basis, he determined that while all emeralds may glow red when a green laser is focused on them, if you look at the spectrum they produce, the energy at which one bright line occurs can differ for synthetic emeralds and naturally occurring emeralds.
Thompson looked at different types of emeralds and spectrum tested each with the laser. He found that the first bright line was almost identical for different emeralds, but the second bright line tended to peak at different energies for each type of emerald. He observed that this second line’s energy position can be used to identify if an emerald has natural origin. For synthetic emeralds this line peaks around a particular energy in the red color range. And while a few natural emeralds also have this line peaking around this energy, the vast majority of natural emeralds have the line peaking at lower energies.
As mentioned, emeralds can be synthetic and naturally occurring. When it comes to the naturally occurring, you have schist-origin and non-schist-origin emeralds. Schist is a metamorphic rock where emeralds can occur. Thompson said emeralds from Columbia are generally considered to be the finest in the world and they happen to be non-schist-origin, whereas, right next door, Brazil also produces emeralds, but the emeralds there form in schist. As it turns out Thompson’s research can also show whether or not a natural emerald is a schist-origin or non-schist-origin simply by looking at the energy of the same bright line.
“What we can do is we can sort of identify the geology- not exactly where it came from in the world, but we can basically sort them into one type of geology or another, and people know what kind of emeralds come from the different types of geology,” he said.
And much like food sourcing, the more you know, the more you’ll probably pay. “The more information you have about emeralds and especially when you’re talking about high-end emeralds, knowledge is money. So the more information you can give about the emerald the more it’s going to sell for,” Thompson said.
Thompson said his research would not have been possible without help and support from major gem-testing labs, in particular the Gemological Institute of America (GIA) and American Gemological Laboratories (AGL). Normally, any expensive gem is sent off to such a gem lab for testing to find out everything about it, including things like treatments that have been done to it and its origin. And so these labs have provided Thompson with emeralds of known origin for testing.
So what is Thompson’s hope?
“I think this research is adding to what we can learn and understand about emeralds.” he said. “In time it may even become a standard measurement for all emeralds in gem labs.”
Thompson said he’s going to continue his research with gems and this month he’ll have his current research on emeralds published in the Journal of Gemmology.
For more information on UNA’s Department of Physics and Earth Science:
http://www.una.edu/physics/index.html