Presidium Refractive Index Meter II (PRIM II) Digital Gemstone Tester | Wide Range 1.000–3.000 RI Measurement for Diamonds, Moissanite & Gem Identification | No RI Liquid Needed, Desktop Jewelry Tool
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FREE 30-day refund/replacement
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Availability:
Only 8 left in stock, order soon!
Arrives
May 3 – May 18
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Features
- ACCURATE WIDE-RANGE GEM TESTING (1.0003.000 RI | Measure refractive index across a broader range than traditional refractometers, allowing accurate testing of diamonds, moissanite, zircon, and a wide variety of colored gemstones.
- FAST, CLEAN & LIQUID-FREE OPERATION | Eliminate messy RI liquidsget instant readings using advanced light reflectivity technology for quick and efficient gemstone identification and separation.
- IDENTIFIES DIAMONDS & SIMULANTS INSTANTLY | Quickly separate diamonds, moissanites, and common simulants like strontium titanite using precise digital RI readings and built-in reference charts.
- DIGITAL DISPLAY + BUILT-IN GEMSTONE DATABASE SOFTWARE | Clear LED display shows instant RI values, while included software features 50+ gemstones and allows filtering by color, hardness, SG, and more to identify unknown stones.
- PROFESSIONAL DESKTOP DESIGN EASY TO USE | Compact, lightweight tester with oval testing platform, blackout cover cup for accuracy, gemstone holder, and USB/battery power optionsideal for jewelers, gemologists, and collectors.
Package Dimensions: 6.2 x 4.3 x 2.8 inches
Item Weight: 7.2 ounces
Department: womens
Manufacturer: PRESIDIUM
Item model number: PRIM2
Is Discontinued By Manufacturer: No
Date First Available: June 1, 2012
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
May 3 – May 18
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Top Amazon Reviews
we like it. there is a learning curve in buying a function specific product. the more you know about gemstones, the better your results will be. as far as product creation, and selling, no problems there. fair transaction, prompt service, quality device. too early to tell about the computer connection.. another learning to do. presently, i see it as being a good tool to add to your bag of tricks, in identifying gemstones. the seller is prompt in assisting you with problems, and need guidance. no device out there, that I know of is the all in one device to identify gemstones. portabel,, easy to use. it is worth the price.
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Reviewed in the United States on July 22, 2015 by Kirby
Works well out of box. Accurate in what it is. For the extra money you definitely get what you get.
Reviewed in the United States on January 30, 2026 by Peter marcucci
When I first purchased Presidium gemstone testing equipment I thought I was getting the best of the best, the price definitely reflects that their products should be top of the tier. After using them over the past 1-2 years there leaves a bitter taste in my mind for their lack of commitment to making a top quality product. I’m guessing it is because they have no competition, and that’s great because it means the company saw a market need and was the first to design and create a revolutionary product and of it’s kind. The product line needs more reliability testing. For some reason a part of me thinks the products are intentionally flawed in clever ways to require repeat purchases from items that fail outside of their subpar 1 year warranty. A company that stands behind their product I would expect to see at least 3-5 years on their warranty. It’s not like these are high powered devices used in harsh conditions, these are usually held gently like jewelry and used in air conditioning for random short periods of time. With that said I have purchased 3 replacement probes for the PGT-2 in the past year. I blamed myself thinking I have been using them wrong but the 3rd one I made sure to be 100% careful and aware of how I used it making sure to press lightly and straight up and down on a flat face of every gem I tested. When the 3rd pen went out sure enough a design flaw was discovered. Inside the pen there is a heated copper wire wrapped in Teflon tubing, the tubing is somehow supposed to keep this jungle gym of wires together but when it heats up and you press the tip down that copper wire flexes ever so slightly and after a certain number of flexes it breaks causing the needle to go all the way over to diamond and it never moves away. All 3 of my pens broke in the same exact spot. Take your failed pen apart and more than likely yours failed there too. That my friend is a warranty issue. I’m not buying a 4th replacement pen. Now onto the Refractive Index meter. The LCD has always been a little dim off and on, then it got dimmer and dimmer till I could barely see a shadow of numbers if I tilted it the right way. Now there is no LCD screen display at all. I can get the screen to show about 10% if I turn it on while holding it at different upside down angles. I’ve tried both USB and batteries and same malfunction. Always taken care of and babied. Never dropped or misused, always on the office table never moved. How do you get an LCD wrong? I’ve found old beat up kids toys with LCD screen that came in boxes of cereal that are still working perfectly.
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Reviewed in the United States on June 4, 2021 by MODiFiEDZ
I sent one of these back because I kept getting erratic measurements with known Moisanite samples. Actually it would many times report RI of 2.42 or 2.65. I thought maybe something came loose during shipment. The replacement did exactly the same thing. What I’ve found is, you need to put the specimen over the sensor hole with tweezers. Doing it by hand seems to throw it off. Anyway, once I got the technique down, I was able to get accurate readings. It’s a good value for the money.
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Reviewed in the United States on April 14, 2025 by Km2455
I really wanted to love this thing. It seems like a well made product, and I have some other Presidium gear that I love. But this thing is just... not at all accurate. It doesn't do what it says it will do. The readings I got from this were NOWHERE NEAR the correct readings for the materials I tested -- and I tested a LOT of different materials, comparing with my regular liquid-based RI meter. The readings from the PRIM II were unusably inaccurate 9 times out of 10. Once in a while, it would give me a good reading. But very rarely. I spoke with Presidium about the readings, thinking it might just be a bad meter, but their general consensis seems to be that the meter's working as it should -- it just doesn't work well. There's some finicky finagling with gems on this -- especially smaller gems (<1/2 ct). Since the sensor looks at a refractive index in one tiny point, you have to move the gem around a bit and find the highest number it comes up with and go with that. LOTS of things trick the light path, though -- inclusions, different thicknesses on the cut, etc, etc. A liquid RI meter balances those out with the liquid. This optical meter does not. The tiniest feather inclusion throws the whole thing off and you get poor readings. It's just... not an effective meter. I had sapphires showing up as Garnet. Peridot showing up as Topaz. Moissanite showing up as Zircon. It just... wasn't good enough to give me even a ballpark on what I'm looking at, even if I KNOW what I'm looking at. An RI meter is only useful as ONE STEP in the gem identification process, but it's a pretty important step. If your suspected green tourmaline has a good refractive index of tourmaline, you can probably narrow things down. But if it's showing up with the refractive index of peridot because your meter just doesn't give the right values, you're left with trying to use a variety of other tests to determine what's right and what's wrong. Having an inaccurate meter like this makes gem identification MORE of a challenge. I'm disappointed, to say the least. Liquid RI meters only go up to about 1.81 in their ability to check for things. That leaves out a good number of gems. But this? This is junk. Save yourself the money.
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Reviewed in the United States on April 30, 2024 by Neil R