Presidium Instruments Gem Tester II (PGT II) with Assisted Thermal Calibration (ATC) for Identifying Diamonds/Moissanites and Common Colored Gemstones
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Color: Presidium Gem Tester Complete Unit
Features
- INCLUDED ASSISTED THERMAL CALIBRATION | Now easily self calibrate your device to your testing environment
- INDUSTRIES MOST TRUSTED | Gemstone tester redesigned to be more compact, sturdy and portable
- THINNEST RETRACTABLE PROBE TIP I PGT II features the industrys thinnest retractable probe tip
- VERSATILE AND RELIABLE | Consistent and reliable results every time. Identifies diamonds/moissanites
- SIMPLE & EASY TO USE | Clear and easy-to-read analog dial; Can differentiate 16 types of gemstones. IMPORTANT TO NOTE | The calibration of this product may be affected during shipping. If you experience issues with calibration, please reach out to the seller for assistance prior to returning the item.
Brand: Presidium
Power Source: Battery Powered
Style: Compact
Color: Presidium Gem Tester Complete Unit
Item dimensions L x W x H: 7.8 x 4.5 x 3.8 inches
Brand: Presidium
Power Source: Battery Powered
Style: Compact
Color: Presidium Gem Tester Complete Unit
Item dimensions L x W x H: 7.8 x 4.5 x 3.8 inches
Upper Temperature Rating: 51 Degrees Celsius
Measurement Type: Thermoelectric probe
UPC: 798804941239 730792705646
Manufacturer: Presidium
Product Dimensions: 7.8 x 4.5 x 3.8 inches
Batteries: 2 AA batteries required.
Item model number: PGT-II
Is Discontinued By Manufacturer: Yes
Item Weight: 1.1 pounds
Date First Available: July 9, 2007
Frequently asked questions
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Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
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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
Color: Presidium Gem Tester Complete Unit
Try to be sure you come at the gem with the probe at a 90 degree angle as much as possible. On small tiny ones try not to let it slip to the side. This thing totally masters knowing what is glass and what is a real gem. Even where readings overlap, you can use possible colors to eliminate the other one or two. I love it. I refused to go pay some old white man $300 to hem and haw then finally used the same instrument. All I mostly need you know is ... is this glass or not? I got one bin for glass non precious and another bin labeled NOT GLASS. The not glass can be figured out when time comes. Get it. It sings YES ! on my old real diamonds. I see so much glass sometimes I just read my diamond 18k hoop earrings to see something real.
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Reviewed in the United States on September 28, 2025 by ChildWhoMadeIt
Color: Presidium Gem Tester Complete Unit
We are not new to gemstones. 25+ years experience. We usually test with refractometer, polariscope, spectroscope, etc. but this is portable and customer displayable. It came today and I tested 100 cut stones with 100% accuracy once I calibrated it and got a feel for pressure and 90* angle on the probe. It tested one of my prettiest cut garnets as glass! *^+}{^*! But I put that garnet under the refractometer and it is indeed glass. I hope I didn’t pay much for that rock. This machine tests thermal conductivity. Pretty reliable method to distinguish Glas from precious stone. But; a lot of specimen species have the same thermal conductivity. It’s really good for telling if that ruby ring is a ruby and not garnet or glass. It’s just a starting clue for identifying “what is this random gem?” It calibrates easily. The case isn’t protective enough, especially of the probe. Tools this low price won’t define lab vs natural - need a microscope and skills for that. Overall it’s a great buy at a reasonable price. You don’t become a Graduate Gemologist with one tool but it’s great for buyers, resellers, and collectors to confirm what you’ve got. Easy to use. Performs outstanding. A touch expensive for occasional use. Treat that probe gently, a new on will cost you. Read a book or two if you don’t know that amethyst and citrine are the same mineral species or that sapphire comes in colors. It doesn’t do opal or organics.
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Reviewed in the United States on June 20, 2024 by Betty Turner
Color: Presidium Gem Tester Complete Unit
It is not as accurate as we hoped and the descriptions are not accurate if glass and all the items below it are the same reading and you have to have the batteries in it as well as being plugged in or it will not work. The point of batteries is so it can be used off site for testing items where there may not be electricity, but guess you can use a power pack. I sent pictures of the box before too, it had a small box with the items in it and then no packing to protect it, so it bounced around and had some damage, have not had long enough to know if work properly or not yet due to any damage that may of caused.
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Reviewed in the United States on September 28, 2025 by jlandino
Color: Presidium Gem Tester Complete Unit
I reached out to Presidium shortly after purchasing this because it would not *read glass...needle didn't budge one bit after calibration. I was told by other purchasers that this isn't right. I was asked to send video and more explanation (which I did)...after sending their requested information (twice), I never heard from them again. I resolved to thinking that mine just read glass as nothing as it seemed to do okay with other stones. Then, one day I went to use it and it just quit working altogether. After warming up, the needle jumped to diamond and stuck there. It wouldn't make any effort to calibrate or anything. I changed batteries to see if that was the problem. Nope...still nothing. I reached out to the company again but so far have not heard a word back. For as expensive as this machine is....IT SHOULD LAST LONGER THAN 18 MONTHS. I will update this review if I ever get a response from them but as for now, I will not recommend this product at all.
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Reviewed in the United States on January 2, 2025 by Janine N.
Color: Presidium Gem Tester Complete Unit
I own an auction company and sell many vintage and fine jewelry. This is exactly what I needed to verify my diamonds and gemstones for listings. Easy to use and works great!
Reviewed in the United States on June 21, 2025 by genemaster61
Color: Presidium Gem Tester Complete Unit
I have been a professional Geologist for over 40 years and this takes the uncertainty out of most gemstones. I do not use the included cord as I don't use the tester it that much. The 2 x AA Alkaline Rayovac batteries last quite a while (not included). I am very impressed. The scale is a bit small for my aged eyes, but that is what reading glasses are for. I believe that the device is made in Turkey and the quality is good. Mine did not come correctly calibrated, but I would have re-calibrated anyway and it is very easy to do. Brief directions are included, or I downloaded the 18 page version from the company website for my alter ego, a professional engineer. It seemed a little pricey, albeit I purchased it anyway. As it works, that is what really counts. I ordered the SmartPro SPGE-I Gem Eye I Gem and Diamond Tester Smart Pro first, but it did not work and they were unable to send a working one after returning it, so I bought this one and had no problems.
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Reviewed in the United States on May 6, 2022 by Bruno Schindler
Color: Presidium Gem Tester Complete Unit
I was able to test that one unknown gem that I had was either a diamond or moissanite. It also confirmed that I some of my other gems that I purchased were actually glass! Grr! For some other crystals that I had, they didn't come back as glass. The sapphire was just slightly out of range, but it was close enough for me. The garnet and quartz confirmations were also helpful. The calibration process is a little cumbersome, but after going through the calibration process a couple of times, I eventually got it calibrated.
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Reviewed in the United States on September 19, 2024 by San Jose Reviewer
Color: Presidium Gem Tester Complete Unit
Pen break easily. No product support that I could find for this issue
Reviewed in the United States on August 26, 2025 by Amazon Customer