PresidiumDuo Tester PDT Diamond Gemstone Tester

Bought in October 2024. And worked a few months with occasional use, but noticed a few times while in the middle of testing a gem, the machine would turn off. I flipped it on and off and it turned back on, but it just happened again, and will not turn on or beep at all. I tried putting batteries in, tried different outlets and will not turn on.

It narrows the field down a tad. I use it mostly to check to see if stones I purchase are even remotely what they were said to be. For the stones that I buy this works fairly well. Like many others review have said, this can not be the only testing you do to identify a stone. But if you 90-95% sure of the stone and just want to have that extra 5-10% for peace of mind than this works pretty well.

Bought this for my wife. We rockhunt. She also test jewelry with it. She has a smaller less expensive tester too. likes this one much better. Seems to be accurate, it's easy to use. It may not be something a pro jeweler would want,( i don't know). But for the layperson. 2 thumbs up.

But it was sometimes dead on and off on other times with known stones. I wish the accuracy would have been better if so this would be a great tool to have.

Straight out of the box the indicator or needle never moved, China has to do better! This was over 400 bucks! So this week after returning the first one, I bought another and low and behold, same issues the needle won't move so disgusted I called Singapore and they said we'll call you back within 30 minutes. Guess what, no call back so this is the second duo tester I've returned. Don't buy from this company. Some things may work but the 2 i bought didn't, and no support afterwards.

So yeah, after reading the reviews I figured it was a crap shoot whether I get a working on or not. Well, no luck for me, as mine wouldn't calibrate. The meter would get "stuck" at certain points which makes it worthless to try and measure stones with. Oddly, the RI reading didn't seem to provide accurate readings either. These issues probably has to do with the packaging that's used for the machine. The device has NO shipping padding and only comes with a nylon case that's ok for lite travel, but would absorb ZERO bumps or impacts during shipping. The testing wand didn't come wrapped in any kind of bag... weird. The probe was exposed; when it really should have some type of cap on it (you know, like pens do...) for extra protection. The manufacturer's cheap and careless packaging is giving a probably really decent tool a very bad name!

HI,My friend bought the presidium Duo tester for me a year back from i gem.it is useless. but it is accurate in testing yellow sapphire and some other stones. This is the report of some stones, which i got checked with this tester last year.After checking the calibration of the tester, This is the chart of stones, which I tested so many times and you can see the results.From number I to 8 tests are satisfactory.But from number 9 to 11 the Presidium Duo Tester shows wrong results.It is very clear that with this tester it is impossible to identify, whether the red color stone is a Ruby or Synthetic stone. and Blue color stone is a sapphire or not.No- stones i tested - PRM test report- Probe pen test report - Result1. Emerald , PRM test 26--- Needle moves toemerald zone. Result ok2. Onyx green color , PRM test 23--- Needle moves upto 25%of green zone. Result ok3. Green color glass stone ,PRM test 13 --- Needle moves upto 20%of green zone . Result ok4. Green imitation ,PRM test report 13 --- Needle moves uptoglass zone. Result ok5. Amethysts ------ Needle moves toAmethysts zone. Result ok6. Ruby PRM test 39 --- Needle moves toRuby, Sapphire zone. Result ok7. Yellow Sapphire ,PRM test 39--- Needle moves to RubySapphire zone. Result ok8. Yellow Colour imitation stone(called Marka in India), PRM test 69 --- Needle movesto Glass zone. Result ok9. Red immitation ,PRM test 39--- Needle moves toRuby and Sapphire zone. Result wrong10. White immitation , PRM test 36 --- Needle moves to Rubyand Sapphire zone. Result wrong11. Blue immitation ,PRM test 37--- Needle moves to Rubyand sapphire zone. Result wrong

I am a beginner working with gems. When I received this tester I took it to my teacher and we opened it together. ( He himself has this tester and recommended to me) He commented to me the pen did not have a cover over the needle when opening the tester. He commented that there were scratches in the lower right corner under the name. At that time he coupled the pen to the tester and said it was not a tight connection it came out very easily. Then plugged the tester in and told me it was not working properly. He show me how his tester worked on a diamond, then mine and it would only register topaz. After several other attempts on other gems he advised me to return it. He said the tester could have been a somebody's return or a lemon from the factory. I hope this helps anyone who's looking to purchase.