Gem Identification Tools and Equipment

 There is nothing more important to a gemologist that his or her gemological testing equipment. For some this may mean a lot of expensive and cumbersome equipment. For others it may mean only a few instruments carried in a shirt pocket. But regardless of how many instruments you require, it is important to be fully aware of the ability of each one to its fullest. Here are some of the most often used gemological testing equipment, and how YourGemologist ranks them in importance.

Gemological Binocular Microscope with zoom lens

These are great if you are always in your office or store. But how often do you do your buying of gemstones in your store or office? These microscopes are great for research, retail selling, and identification of difficult gemstones such as some synthetics. But no gemologist worth their salt should rely solely on one of the big, expensive monsters for synthetics, anyway. If you are in the field (or out on the streets) they are difficult, if not impossible, to carry. And you will almost never find a plug when you need one. Best to train to grade and identify gemstones with a 10X hand loupe. Then, when you get asked to make that special buying trip to the tanzanite fields of Tanzania, you won't have to pay extra air fees for your luggage that is overloaded with your microscope. And....where are you going to plug the damned thing in, anyway! Save your money on a moderate scope for the office or store, and put your money into something useful like a full size spectroscope...or more inventory for your store. Let's face it, has anyone thought about why the New York Diamond Dealers Club does not have rows upon rows of big expensive microscopes lined up on the tables. Because they don't need them.

10x Hastings Triplet with Bausch & Lomb Lens and Diamond Gauge

This is the instrument of choice of the best gemologists. With this set up you can separate synthetic moissanite or cubic zirconia from natural diamond, clarity grade a diamond, cut grade a diamond...and you don't have to plug it in anywhere. Fits in your pocket. Show me a gemologists who can't do a complete diamond analysis with just the instruments at left, and I will show you a gemologists who is not worth much on a buying trip. Learn to grade with just a loupe! It will be the greatest benefit to your gemological ability that you will learn.

Mag Light with Dark Field

If you want to be creative get yourself one of the cool MagLite's with a dark field illumination attachment. It has a built-in 10x loupe that works well. Its meant for those of you who need dark field illumination to do clarity grading, but are smart enough to know better than carry a microscope around with you in your luggage.


These are great tools if you are in the office or store. But where are you going to get a light source if you have to take it out of the office...from your polariscope? Oops, there's already another piece of equipment you have to carry. Even the "portable" versions are a headache. The refractometer is best used in the office or store with a sodium "D" light source. This gives you the best and most accurate reading. No sodium "D" light source?...put some table salt in a candle. Works just as well and is a whole lot cheaper once you get good at using it. But for travel, these just don't work. There are the Jemeter below....

Jemeter (infrared reflectance meter)

Now here is a tool never to leave home without. Although it is not taught much in the United States, the Jemeter is the best tool for testing refractive index of a stone. Its digital, it runs on batteries so its portable. And it will read far beyond the 1.79 reading of the normal glass version of refractometer. And it will also test for birefringence so no need for a polariscope. It requires some care to maintain calibration...but then if you are going to own gemological equipment you need to get used to caring for your equipment anyway. And how difficult are they to use? I carried the one in this picture for over 10 years and 400,000 miles around the Caribbean. Never failed once. And not once did I ever carry a traditional refractometer in my suitcase. Did not need one. To learn more about the infrared reflectance meter take the gemological courses of the Gemmological Association of Great Britain. Its the best in the world.


Again, great around the office to make quick determination of single or double refraction. But most gemologists don't use it to its fullest extent, that being with a conoscope to determine optic character. But a nice instrument to have for SR or DR stones. But let's face it, the most use these really get is for a light source for the refractometer. If you want to spend the money get one to look good for the office. I haven't used mine in 10 years...except to teach students how to use them if desired.


Very useful tools that no gemologist should be without. Critical in identifying many synthetic and imitation gemstones. But sort of expensive for what they are...two pieces of calcite set opposite to each other. But still important no matter. Don't travel without one.

London Dichroscope

Or, you can get the same result for about 1/5th of the price. The British came up with a dichroscope that is based on polaroid filters. Works as well as the expensive counterpart above, but costs much less. And if it gets ripped off during travel, easy and inexpensive to replace.

Chelsea Filter

Never, never, never leave home without your Chelsea Filter. As a GIA Graduate Gemologist I can attest to why the GG's of this world do not understand the Chelsea Filter...the GIA does not teach it. It is perceived as some ancient filter once used to ID synthetic emeralds. Not even close! The Chelsea Filter can separate every tanzanite imitation on the market from the real thing. It can identify the chromium content of Colombian emeralds, give a red reaction to natural Lapis Lazuli, show chromium content of jade, separate synthetic blue spinel from natural. So many, many things this little filter can do that US gemologists don't even know about. Learn about this very important gem identification tool. It is one of the most important tools that will keep you from having to lug all that heavy, electricity eating equipment around with you when you travel. I keep 20 of them in my office in case I lose one.

Master Colored Grading Set

In your store or office these should be diamonds. But few gemologists are gullible enough to travel with a set of master color grading diamonds. I have used a couple of sets of color grading CZ sets for years. I check them on an ongoing basis with an AGS Master Set that I have access to. So far, no changes in color, in spite of what some places will tell you. If you travel, stay with the CZ master sets.


Never, never, never leave home without your spectroscope. Unfortunately, this is another piece of equipment that the GIA falls far short with their training. A gemologist that is well trained with a simple hand held spectroscope can identify so many, many gemstones that it might amaze you. And I mean with nothing else but a hand held spectroscope. That is some training that will serve you well in buying, appraising, and identification of gemstones in the matter what field you are standing in.

Specific Gravity Liquids

These are important for identification of a lot of the office or store. But try taking some on a trip with you! And leave them to sit for a while, and then go back to check if they are still accurate with their SG measurements. No way. You have to start pouring in a little methylene iodide..a little bromoform...a little of this...a little of that. What a headache. Get yourself a carat scale that will hold an attachment and get your specific gravity the old fashion way...hydrostatic weighing. Its more accurate and a lot cheaper. Save your methylene iodide for the immersion cell.

Electronic Scales

God Bless The Japanese and Americans for developing some digital, electronic scales that are accurate and durable. The carat scale on the far left is from the US company: Dendritics, and the gram/pennyweight scale on the immediate left is from Tanita in Japan. Both have traveled the same 400,000 miles as the Jemeter above. And never once failed and never once got out of calibration. Thank you Dendritics and Tanita. Well done!


Ultraviolet Cabinet and Long Wave/Short Wave UV Light

Again, a great tool for the office. But there are several models on the market today that run on battery, give you the same light sources in a far smaller, hand held light source, and don't take up near as much room. There are a number of models out there so find one that is right for you. But by all means get one. You will need it.

Electronic Metals Tester

Be very careful about these testers. If the reaction is good then you can probably trust the tool. But if it says not good, that means get another opinion. These are as good as the gemologist using them. Which means everyone should be careful. They are better than trying to carry a vial of hydrochloric or nitric acid around with you. But take negative readings with a grain of salt until you get verification from, preferably, an aqua regis test.

Leveridge Gauge

This has been a staple of gemological tools for decades. There are now a lot of fancy digital version on the market which makes it better for old guys like me to read the measurements. But I would not suggest that any gemologist be without one. They are vital in making weight estimations by measurement formula. Spend the money to get a good one. It will be money well spent if you take care of it.

Geiger Counter

Yes, there are radioactive gemstones out there. Some with so much radiation that they can make you sick enough to light up in the dark. And since the Cold War seems to be over, there are a lot of very fine condition 1961 Geiger Counters on the market. I strongly suggest you find a Victoreen CDV700 model as shown at left. This one will read lower radiation levels that gemstone will offer, while some of the CDV720 and higher models will not. The one shown here was obtained on eBay for about US$75.00. Be careful out there.


These are the basics when it comes to gemological equipment. How much or how little of it all you need will depend on how experienced and how well trained you are as a gemologist. By far the best training you will find for gemology without the need for a lot of expensive equipment is with the International School of Gemology or the Gemmological Association of Great Britain. Both teach you to understand the "why" of gemology so you don't need to carry a lot of heavy equipment, and you don't need to carry a lot of reference books. I highly recommend them to anyone interested in gemology. YourGemologist

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Robert James FGA, GG.....YourGemologist