HMKISDiamond Tester Pen, High Accuracy Jewelry Diamond Tester＋USB 9V Rechargeable Battery＋ 60X Mini LED Magnifying, Professional Diamond Selector for Novice and Expert, Thermal Conductivity Meter

It really works!!! Charge battery first until green light ready to use. Be sure to follow the instructions carefully and check room temperature- away from windows. Be sure to clean gems with cloth (remove dirt or oil) before you test them. When you are not using a diamond tester, remove battery. Always charge battery first whenever you plan to use a diamond tester. I can test moissanite jewelry from Amazon to be sure they are real! Yay

Saved us 3k by taking it with us and testing a ring that was a private seller with no near jewelry store.

I am trusting that this diamond tester is accurate. The instructions were a little challenging, but once I understood it is easy to work with. I also appreciate that it is a rechargeable battery for the charger.

This has been accurate on real diamonds. Not so accurate with other things it claims such as different gems/different ranges. Everything else from a glass bottle to cz to a real sapphire tests all the same. But you hear the beeps when it detects real diamond so it will detect diamond. Would I rely on it solely? No. You still need good observation skills & a good loop to double check. This is a good quick starting point though.

As a gear nerd. This is a good product. I don’t use the rechargeable 9v. You will have better results with just putting a high quality 9v in there. Didn’t see how controversial it would be but. Got zero problems, works great and reliable.