Gold & Silver Forum - Acid testing?

"Acid Testing" in only a skin-deep process at best. To really check a coin for correct gold content requires an accurate specific gravity test (harder to do once alloy metals are employed) or a totally destructive test on the coin itself. Just dabbing a bit of acid on a coin tells you only one thing......that the surface of the coin in that particular spot contains gold. It doesn't tell you what is INSIDE the coin. To test that, you have to damage the coin to test the interior of the piece with the same acid testing process.

The very best method of coin testing I have found over the years remains the FISCH instruments, the little "counterfeit detectors" that were designed on the basis of very similar devices used back into the 1700s and 1800s that incorporate quick specification checks for shape, thickness, diameter, and correct weight (specific gravity) based on the alloy involved. I keep these handy for Krugerrands/Gold Eagles, Pesos, and Sovereigns, the coins I trade in most often......(mostly Krands). They are cheap insurance, non-destructive, and very fast to use. No acids, no fumbling with scales, no second guessing color or specifications of the coins. They either pass or they don't, simple as that.

In short, acid tests are not at all reliable unless the coin is damaged, and that kind of defeats the purpose IMO. There are also different acid mixtures or types to check for different karatage of gold content, such as are used with touch-stone testing. Even then, the best you can expect is a general "range" of possible karat value.