Please note the review below is from 2010. I might give these a 2nd chance 3 years later, but I eventually moved to an electronic tester and only use acids for silver and (rarely) platinum . . .
I purchased this just a few days ago. EZSell got it to me really fast and in good shape. However I have some problems with this product. It seems that either my acids were old out of the box, or they were terribly mislabeled.
The acids should get stronger as you go up in karat. The 10K acid had no effect on marked 14K - this is correct. the 14K acid bubbled and emmitted a brown cloud over the jewelry. This would indicate that it was mismarked, and lower than 14k gold. I pressed on. the 18K acid only had a mild effect. This would indicate that the bracelet was in fact 18k gold, even though it was only marked 14k and the 14k test and said it was even less than that!. Ok finally I tried the 22k acid. I got a pretty big effect and color change After repeatedly comparing I determined that the 14k acid was stronger than the 22k acid.
So this means Only the 10K acid was properly labeled. The 14k acid was actually 22k strength. The 18k acid was actually 14k. And finally the Acid labeled 22k is actually the 18k acid.
Once I figured that out the kit worked fine. The silver solution worked as it should. I don't have any platinum to test. Next time I'll buy one of the kits with white tops. Stay away from the colored tops. If they couldn't get the acids in the right bottles, how well did they measure the acid mixture?