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Is That Tanzanite Real or Fake?

by Steve Moriarty March 29, 2018

Hi Everyone!

Today's video is actually a redo of one we did in the past. We got some thumbs down as we weren't clear enough with some of the things we said, so we have done a brand new video that goes real in-depth to finding out if Tanzanite is real or fake or of course imitation or synthetic. Please let us know what you think!


Hi, I'm Steve Moriarty from Moriarty's Gem Art. We're a jeweler on the square in Crown Point, Indiana. We also represent ourselves online as Today we're here to give you some assistance in how to identify tanzanite. Tanzanite here is a natural gem and here is the rough crystal of tanzanite. The difficulty in separating these visually is a problem, but with a little bit of equipment you can make separation.

The problem is that there are several gems that kind of duplicate the color and somewhat the appearance of tanzanite. Many tanzanites you can visually look at and you know it's tanzanites, but sometimes in the medium and lighter colors it becomes difficult. The gems that we have to deal with that are imitations for the stone, and I say imitation because there is no synthetic for tanzanite, synthetic like in synthetic sapphires, synthetic ruby and emeralds. If you grind them up they are exactly the same, man made one, nature made the other. So a synthetic is very difficult to separate. But we don't have to deal with that in tanzanite. No synthetic, only imitations and imitations can be separated by optical equipment that we have here.

The equipment that you can use, the imitations that are a problem would include glass, spinel, yttrium aluminum garnet which is YAG. Synthetic sapphire, synthetic forsterite is probably the biggest issue in identifying because its characteristics are a little closer to tanzanite and the look is better and it's the most commonly used imitation for tanzanite. Then we have a natural gem called iolite which somewhat has the appearance of tanzanite and can confuse you.

Our first piece of equipment would be the 10 power loop. This is a Hastings Triplet. This particular loop might run you $40, but you can buy a good 10 power loop for around $10. In identifying tanzanite, this really only has one purpose and that will separate forsterite, which forsterite is the most commonly used imitation of tanzanite. The way you do that is the forsterite has the characteristics of being strong birefringent, meaning that it really separates light into two rays pretty strongly.

So as you take your sample and you look through the crown facets, which is this is the table and the crown facets are off to the side of the table, you look through the table to the facets on the back of the stone and as you're looking through it you can see the lines that the facets make. In tanzanite those lines are going to appear as one straight line. But in forsterite what happens is because of the strong separation you'll actually see two lines close together, mirror images of each other. It's just every facet line will have two instead of one. There's only truly one there but when forsterite bends the light as much as it does, you actually see two. So that is one separation for forsterite.

Not much good on the other imitations, but the 10 power loop is, of course, good for many things that you're going to use if you're buying gems just for identifying inclusions, seeing how the quality of the polish is. So it's a good piece of equipment to have and very inexpensive.

The next piece of equipment can be expensive. This is a refractometer. This is a jeweler's go-to device. It will separate 90% of every gem that we get. The ones that are the biggest problems would be synthetics. A synthetic is the same as the natural gem only man made it. Natural gems were found in nature, but they are duplicates of each other. So what this instrument will read will be the same for synthetic as it is for the natural gem, so it doesn't help for that.

But with tanzanite we're not dealing with that issue. We only have imitations to deal with. And what this will read will be different for every imitation that you could possibly deal with. How this works is you need a drop of refractive index fluid. You put the gem on the hemispheric carefully because it scratches easily. Close it up, turn your light on, and you look through here and you'll see a scale on there and it'll read out a number and that number as you look on the side of this instrument, every gem has a different number. So you can pretty much identify all the imitations of tanzanite using this piece of equipment. Generally the problem is that it's an expensive piece of equipment. This setup is over $1,500 to buy it.

But recently I've found this instrument, which is the ADE Advance Optics Refractometer and I take it with me overseas whenever I go because it is a relatively accurate refractometer that you can buy for under $100. So it is something that all of us can own and if you're into dealing with gems it's something you should own. The refractometer will pretty much separate all of these gems, no difficulty with any of the list.

But the next piece of equipment will also separate all the tanzanites for you and this is the tanzanite filter produced by Dr. Hanneman, Hanneman Gemological Instruments, another piece of equipment that's inexpensive. This is under $40 delivered to you from Amazon. So this piece of equipment, the loop and the refractometer which will identify most things that you could want, including tanzanites and their imitations, you're dealing with less than $150 for all of it.

This tanzanite filter is a very useful device. Not only does it give you the tanzanite filter, it also gives you a dichroscope. My dichroscope costs $80. For $40 you get the tanzanite filter and you get a dichroscope with it, what a deal. So this side of it, this film actually works as a dichroscope and here's your tanzanite filter. So the dichroscope will be helpful with the singly refractive gems, which would include glass, spinel and the YAG because when you look through these, where dichroic gems will show two colors and in the case of tanzanite can be three colors, a singly refractive gem like the glass and spinel and YAG will only show one color so you can automatically weed those out from being tanzanite just by using this dichroscope.

The other half of the filter is the tanzanite filter. So when you look through the filter what you're going to see is these colors for the different imitations and it will separate most of the imitations, especially when you combine it with the dichroscope. So just this filter is very useful in separating almost any of the imitations that you could use.

So you can see there's several ways of identifying it and a couple of the pieces of equipment include even the tanzanite filter and the refractometer will separate all the issues you're going to have with whether you have a natural tanzanite or a fake. One thing on the refractometer is that mounted jewelry sometimes can be done, but sometimes it's a problem because you can't get it to lay flat on the instrument and it does take a very flat facet to show readings. So a poorly cut stone may also be an issue with the refractometer.

So from here we're going to show you some of the things that the dichroscope does in this Hanneman filter, just a real handy device that's going to be useful in other gems you may buy also. A real good quality instrument, I take this when I travel all the time because it's a small instrument that can go anywhere and can identify many, many stones.

This is what the dichroscope does for you in all dichroic gems. The single refractor gems will only show one color, but this is just a very useful tool that anybody into gems should own. The three pieces of equipment that I've recommended to identify tanzanite, whether natural or fake, costs you $150 and well worth owning to help you in all your purchases of gems. Or take that money and come shop with us at

Steve Moriarty
Steve Moriarty

Steve Moriarty has been in the jewelry industry for over 30 years. Steve is not only a jeweler, but a gem cutter and designer. He has traveled the world in search of gemstone rough and has owned a retail jewelry store for 20 years located in Crown Point, Indiana.

2 Responses


August 28, 2020

Re: Refractometer: The side panel does NOT show every mineral. Tanznite is missing from the list!

Barnabas Moshi
Barnabas Moshi

January 07, 2019

A very helpfull explanation

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