Review on 💎 Expert-Recommended: High Accuracy Jewelry Diamond Tester II with Thermal Conductivity Meter - Ideal for Novices. Includes 9V Battery! by Amy Mcleod

Overall this product works very well. I'm amazed at the number of false alarms. Yes I have a positive contact with the stone table but maybe 1 in 20 will be a false negative. Shutting down the tester, waiting, restarting, and testing again usually helps, but it worries me. My biggest complaint is that the very high pitched tone for a positive test is usually not audible to me. My wife can hear it in the next room so volume isn't an issue, but for me, a vet with multiple acoustic injuries, I can't hear it. I am by no means deaf, but very high frequencies are beyond my hearing range and I believe this is true for many other veterans or people with a history of acoustic trauma. Thank God there are red lights, which also confirm a positive result. Generally this works well, but watch out for false negatives and do some testing before rejecting a stone as a simulant.