How to Use an Acid Test for Gold

Nitric acid applied to copper, which all imitation gold jewelry contains, turns the copper green. If no chemical reaction takes place, the metal tested is gold. Gold-content stamps were not required on jewelry by United States federal standard until after 1900, so jewelry produced earlier may be without identification of the metal content and still be authentic. The only way to be sure is to subject the metal to an acid test.

Things You'll Need

• Nitric acid
• Heavy rubber gloves
• Apron
• Gold
• Clean cloth
• Running water

Instructions

1. Purchase nitric acid, packaged in a dropper bottle, from a chemical or laboratory supplier.

2. Don thick rubber gloves to protect hands from the corrosive nitric acid, and an apron to protect clothing and the skin beneath.

3. Apply a drop of nitric acid to the surface of the subject metal and wait at least 10 seconds.

4. Watch the color of the metal where the acid drop is located. If the metal has changed color to green after 10 seconds, the metal contains copper and is not gold. If the metal remains gold-colored, the metal is actual gold.

5. Wipe off the acid with a clean cloth and dispose of the cloth. Wash the metal in running water to remove any remaining traces of the acid before removing the gloves and protective apron.

Tips & Warnings

• Nitric acid will burn skin and clothing. Always wear protective gloves and clothing when using.

References

• About-the-web.com: Test for Gold
• ScienceStuff.com

Resources

• PBS "Antiques Road Show": Authenticating Gold and Diamonds