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

Instructions are clear. Works well. It can be hard to get the stylus not to slide off of a polished tiny stone in a setting. I feel much more confident selling jewelry with this device.

ABOVE 5 STAR RATING I WOULD MARK THIS IF GIVEN THE CHOICE!! Great once you get the hang of it. That probe does easily slip off the stone. I just wish the print was larger where it shows the reading when you do a test on a stone. Also would be nice if it made more of a pleasant sound when the probe hits something that it should not. The sound it makes is very annoying. Even with all that being said I would still rate this item 5 STARS plus as it is very accurate. I thought mine was broke until I RE-READ the manual. A stone will not register correctly if it is loose in the setting (TRUE). Another HELPFUL hint I found & would like to share is.....The probe is very sensitive & will give you an inaccurate reading if you are trying to use it underneath a CEILING FAN that is running. So just make sure to not having any moving motions around you.

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.

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.

This unit does not even turn on when connected with the power cord. It doesn’t seem to have that problem using battery power only. However as soon as the power cord is attached to the unit it shuts off immediately. For the price of it, I would think Quality Control could be better. Using the battery power only, I was able to test many gemstones and found this Presidium Gem Tester II to be accurate and easy to use. However, being unable to use it with it’s power cord is a real problem for me. Update: I’ve had this Presidium Gem Tester II for a couple days now. I can turn it on using battery power, it blinks red for 30 seconds or so and then shuts itself off. Tried several times, removed and replaced batteries and tried again. Red light blinks for awhile and then unit shuts off. Really upsetting! I contacted Presidium yesterday and still waiting on a response.

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.

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.

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.

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

Thank you , so fast

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