How does a touchstone on jewelry work?

Written by Jewelry on March 12, 2010

I need to know the physics behind how a jeweler can tell the authenticity of jewelry by using a touchstone. Can anyone explain this to me, even if you don’t know a whole lot about it?

One Comment to “How does a touchstone on jewelry work?”

  1. Physicsmom
    12:26 am on March 12th, 2010

    A touchstone has a finely grained surface on which soft metals leave a visible trace. The trace will react differently to specific concentrations of nitric acid, thereby identifying the quality of the gold. Thus 18 Carat (purity) gold is not affected but 14 Carat gold will show chemical activity.

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