Interview with Gemologist Cara WilliamsInterview with Gemologist Cara Williams

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Interview with Gemologist Cara Williams

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In a recent phone interview, gemology tools expert Cara Williams of Stone Group Labs discussed the myriad tools available to gemologists today. Learn about the most important tools of the trade and what it's like to be on the leading edge of gemology.

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Lab with advanced gemology tools
Stone Group Labs uses numerous spectrometers and other advanced equipment. © Stone Group Labs. Used with permission.

A Wide Variety of Gemology Tools

Running a gem lab, you must have a lot of experience with a variety of gemology tools.

Well, when you just call it tools, there's a whole host of other little things too — tweezers, stone shovels, tons of little things you need.

Then there's the gem testing equipment that a retailer or appraiser would have on hand. That's your standard microscope, refractometer, polariscope, dichroscope, spectroscope. These are what I like to call the "analog" instruments.

And there's traveling equipment, too. This is the pocket equipment that a lot of traders use out in the field or when they travel overseas. You don't really want to bring a bulky microscope on the plane, but there are a ton of useful little tools, like a darkfield loupe and a Chelsea filter.

There's really a wide variety of testing tools out there, too. A lot of little tools have come on the market that aren't basic gem testing tools, and some of them overlap in what they're helpful for. Some have a single purpose, some aren't so accurate. Many such tools are focused on eliminating certain IDs, rather than actually telling you what you have.

But what we work with most of the time is the advanced equipment. The most recent generation of gemology instruments are various advanced spectrometers that work off of different fields of physics and different ranges of the electromagnetic spectrum. All rely on software to interpret the data into a graph or digital spectrum.

How an Expert Picks the Right Gemology Tools for the Job

What's the daily work like in the lab?

It really depends on the gem! We're a colored stones lab, so we don't do much with pearls. We do some diamonds with the advent of so many synthetics entering the market, but that's really occasional. With colored gems, we look for something different every day.

Whatever we're looking at, the first instrument is always the microscope. It narrows the focus of what to approach. There are two different schools of thought in gemology. Some recommend doing the same tests, methodically, every time. I consider that a waste of time and energy. If you can eliminate options more effectively and diagnostically, we try to be smart about it.

So, how do you choose the next instrument to use?

Well, it really comes down to experience. When you've looked at thousands and thousands of sapphires, thousands of tanzanites, and thousands of iolites, your brain picks up subtle details. There are differences in precise color, pleochroism, refraction, and when you look at these stones constantly you can tell. Your brain subconsciously registers these subtle differences. It's an interesting and helpful exercise to try to become more aware of this process, but in daily work, it just comes to you. So, your experience will tell you which tests make the most sense to confirm the ID and which tests to do next to confirm any possible treatments.

But you really need to know all the possibilities before picking the next test. You can't conclusively identify a material if you don't know what all the possible options are — and until you can eliminate all options except the correct one. I see many inexperienced gemologists try to force their test results to point to an incorrect ID because they didn't consider it could be something entirely different.

On the Leading Edge of Gemology

What happens when there's a brand new treatment?

For most treatments, you can tell by the gem's appearance combined with all test results. Often, something doesn't quite fall in line. When you have the experience and come across a new treatment, test results don't match your knowledge of the material — its geological formation, its common chromophores, etc. Something won't look right under the microscope. Raman spectroscopy is a helpful indicator, too. It can identify the underlying mineral, looking beyond surface treatments or appearances.

For example, CVD coatings on topaz are getting very sophisticated. They used to be easier to detect, but now even some experts can be fooled. Raman will tell you, though, if it's just topaz, whereas the surface treatments may prevent accurate refractometer readings and visual clues.

But we do get some stones with new and secretive treatments, especially in cut form. There's some fraudulent rough, but most of the time it's a miner submitting a stone like, "I pulled this out of the ground and have no clue what it is or how to market it fairly." So, most of the time the rough we receive is very honest.

On the other hand, our investigation of smoked opal was very unusual. Since most opals are untreated, labs don't commonly look at them. As a result, many labs don't have a lot of experience with this material. Even after we sent out our bulletin on the smoke treatment and how to detect it, a lot of labs weren't catching the treatment. Unless you know what to look for, it's easy to miss. Occasionally, a lab must take a step back and look at the bigger picture. Now, with actual untreated Ethiopian black opals, things get even more complicated.

With new treatments, a lot of times it's just that things aren't fitting into a pattern. Even then, you can't get too complacent with pattern recognition. That's one of the problems with rote testing. If the treaters know your tests, they can find a way to get past them.

Sometimes, we don't publish our testing methods because the treaters will just be able to get around them.

Oh, wow! So, if you don't publish a new treatment, do you contact other labs about it?

At pretty much every major lab there's someone we know and would consider a friend. So, most of the time we'll spread the information that way. But we also have certain proprietary knowledge, too.

Part of what we do is try to keep an honest and level playing field. The role of labs is really to maintain the integrity of the industry. That's why it's so important that labs get things right.

Favorite Tools and Toys in the Gem Lab

Do you have any favorite gemology "toys"?

Oh! [Laughing] Yes! I have this fabulous microscope. I had it built just for me. You know how most microscopes are like looking through a dark tunnel? This one is amazing. It's like looking into a bright, well-lit fishbowl. I can see everything.

A good microscope will always be the best tool for a gemologist. Especially with all the different accessories. Different kinds of lighting, attachments, filters — there's so much you can do with a good microscope.

As for the more advanced equipment, the FTIR (Fourier Transform Infra-Red) might be the most important machine in the lab. We've done a huge amount of research on this. The first one we got wasn't built specifically for gem purposes, so we've had to tweak it a bit, but it's just a workhorse.

Then we got a Gemmo FTIR. This one was purpose-built for gemology. We find we're using it more and more. It's really great and comes with a nice industry-specific database.

Expert Advice for Gemology Tools Novices

What advice do you have for someone who wants to pursue a career working in a gem lab?

[Laughing] You know, there are always people who want to come work in a gem lab, even for free! But as a career, it really requires more than a love of gems. There's a lot of science you need to understand to really do well in gemology. Some crystallography, geology to understand how the gems form, and especially chemistry. You have to think scientifically and not be blinded by gem values or the stories that accompany some submissions.

Understanding chemistry is so important. It will tell you so much — how gems get their color, what inclusions can form, what changes when a stone is heat treated or irradiated.

But a lot of things about gem labs aren't the same as in other fields in the industry. Working in a lab is completely different from being a trader. It even differs from traditional gemology careers in appraisals or retail. You really have to have a different sort of disposition. There's also great responsibility and liability with small, valuable items.

Addison Rice

A geologist, environmental engineer and Caltech graduate, Addison’s interest in the mesmerizing and beautiful results of earth’s geological processes began in her elementary school’s environmental club. When she isn’t writing about gems and minerals, Addison spends winters studying ancient climates in Iceland and summers hiking the Colorado Rockies.

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