Review on VCCA High Accuracy Jewelry Diamond Tester II: The Ultimate Thermal Conductivity Meter for Novice and Expert Gemstone Selection by Sasha Hsiao

I bought it for my grandson who is interested in gems and minerals. Elsewhere I bought a reasonably priced rough diamond to add to my collection. I tried it today and it's fantastic! As other reviewers have warned, you must read and follow directions or you will not get accurate readings. It's not difficult at all. You just have to know how it works. Each time he identified the diamond very accurately, no matter how hard I tried to confuse it with other stones :) I think now my grandson has to take it away from me. And my husband need to buy me more diamonds for testing.