Instruments Gem Tester II (PGT II) with Assisted Thermal Calibration (ATC) for Identifying Diamonds/Moissanites and Common Colored Gemstones

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.

This is the go to for lots of my peers who collect or sell ewelry and gemstones. I'm very pleased with it.

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.

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.

Unfortunately, like many others, my window of time to return it is over. It worked great the first time I calibrated it and used it. Put it away as carefully as possible. A week later I try using it again, then it's telling me everything is a diamond--so I try to recalibrate it, but it won't. I contacted company and they said they would send me a new probe after I answered like 10 questions. I will say they responded quickly and I was very happy with that. Took a while, but I finally got my new pen and it worked fine. I used it twice in a week and all was good. Then I took it out after 2 weeks or so and started off fine but then again it was going haywire! I am getting ready to contact company again, but I doubt they will help me again because my warranty window closed a month ago. I have owned it for 2 1/2 months. Very disappointed because I need a gem tester to test my jewelry I sell on ebay. I will either buy a new pen or see how much I can sell it for without a working pen/probe:( Very frustrating. Like others said, if you buy it make sure you use it often before the warranty expires so that you can decide if you will keep it or return it.

I love this tester and it's easy to use. I am well aware of how delicate the tester point is, so I am VERY careful with it and keep the tip cover on when not in use. This is a great item to have on hand. You can test all the gems you're unsure about... and do the same for your friends. It comes in a nice case and is easy to store. I had a tester for decades before this one, but it just tested diamonds. This one does so much more and the price is so reasonable. Treated right, you will have it for years and years. AND... it's so easy to use!

Great item. Be careful with tip as delicate. I’m considering buying an additional tip just in case mine gets broken

A neat tool to have in checking for diamonds (and some other stones) but hard to read between some types of gems as the identification bands overlap. It is, however, VERY good at diamond testing and if you have some knowledge of gemology it is helpful in testing other stones as well. Very good at ID-ing glass and plastic, so it is good to have for that alone when looking at old costume stuff. Calibration is easily accomplished and it holds for several operations. Battery life is sufficient for a days worth of flea-marketing.

The Presidium was everything that I expected. Works well and the calibration instructions were easy to follow. I have only one suggestion for improvement and that is to value add by offering a US-to-Australia power plug adaptor.

لقد تم تجربة المنتج على احجار اللماس صحيحه ١٠٠٪؜ ولم يعطي نتيجه صحيحه كل ذلك اقل بنسبة ٣٠٪؜ وهاذي نسبة تخلي الواحد يتراجع او يفرط في قطعه ١٠٠٪؜ صحيحه والشي الاخر لم تتم اعادة المبلغ الى الان مايقارب ١٤ يوما واكثر ولا زلت انتظر وكل يوم اتصل ولا احد يفيدني

When I received this I tested all my known gemstones, as well as gemstones purchased from eBay. I was not surprised to find that stones that were purchased at a discount price as rubies, tured out to be spinel. I was not surprised because I am fonder of spinel’s brighter magenta colour as opposed to ruby’s pigeon blood. Combine this with a specific gravity scale as your secondary line of testing and you are covered. The manufactuer provides clear instructions for calibration, as well as a small tool for depressing the hidden calibration/reset button under the little rubber cover on the right hand side of the machine. Happy with my purchase, hope it serves me well for years to come.

الجهاز جيد ويعمل دون أي مشاكل، لم استفد منه بشكل كامل لاني استخدمته لفحص الصخور والاحجار في صورتها الاساسيه وليس المجوهرات والمشغولات كما يفترض.

Muy buen producto funciona de maravilla