Presidium Instruments Gem Indicator (PGI) Handheld Tester for Identifying Diamonds and Common Colored Gemstones

Great tester, as other reviews have stated You have to have some Knowledge of Gemstones while using this pen which I had no problem with, you can go on the Presidium Website and Download the Spreadsheet of Gems if you’re not sure. As far as Diamond if I wasn’t holding the pen straight and at an angle it would read Sapphire and Ruby, you need to hold the Tester at a straight angle to get an accurate reading, held straight tested for only Diamond. I just wish this one Included an option for testing moissanite!

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I found this gem tester to be very inaccurate in that it gives you a wide range of possible stones. It also has a very difficult time with blue and green stones calling them glass most of the time. For the $300 plus price I expected it to be more accurate and informative. I have an RI tester that is so much better but is hard to use on smaller stones. That was my main reason for the purchase of the new tester with a small tip. It will press against small gems but the readings are not very accurate.

I found that when using this product, it works every single time, every gemstone that I used it on came back with the exact right name. Some people have been giving bad reviews about this product.I feel that they weren’t using it right, or didn’t read the instructions all the way that you have to download, or they need a new tip.

I was worried because of some of the other reviews but I got this product and it is an excellent diamond tester. It can also test some of my Amythyst and even showed me that a few family heirlooms were glass hahaha. It doesn’t say Cubic Zicornia but it will give you the same 8 options so you know what it means. And most importantly, if you test CZ, diamond will not be one of those options!I’m happy with it. Definitely recommend. It can test rubies and sapphires too.

I can’t get this thing to work properly for the life of me. It won’t stay charged, it won’t directly identify stones…overall it’s a piece of junk.

Works good

Challenging to figure out… Did not seem accurate