“Real” gold in the U.S. is categorized as a gold substance that is 10 karats or higher (or 42 percent gold or higher). “Real” silver jewelry is marked with a 925 somewhere on the surface of the jewelry, meaning it is 92.5 percent silver. For the most effective quality testing, take the gold or silver jewelry to a quality-assurance lab or trained jeweler; however, there are also some tips and tricks that you can try at home.
Check the jewelry for the proper markings. Gold jewelry is typically stamped with its karat amount (e.g. 10k, 14k, 22k), whereas silver is typically stamped with a 925 or higher (up to 1000), indicating its purity. The stampings cannot independently confirm that the jewelry is real, but it does help close a credibility gap (i.e., jewelry without the stamps is far more likely to be fake than jewelry with the stamps).
Wear the jewelry for some time, making note of any discoloration. If the gold jewelry creates black markings where you wear it or turns green on any part, then it is likely fake. Real silver, conversely, turns dark when exposed to the air for too long, meaning that if silver stays silver when worn outside for a long time (e.g. weeks), then it is likely not real.
Hold the jewelry up next to a magnet. In addition to the gold or silver, the base metal in jewelry is typically cooper, tin, or nickel, none of which responds to a magnet. Only iron or iron alloys are attracted to a magnet. If the jewelry does not stick to the magnet, then it is likely real.
Take the jewelry to a trained jeweler. The jeweler will likely compare the sheen of the gold or silver jewelry to other jewelry she owns and may even complete a nitric acid test or sulfuric acid test, which requires placing small amounts of either acid onto small cuts of the jewelry and observing the changes. If the acid creates a white milky substance, then the presence of silver is indicated. If the metal completely dissolves, then the piece of jewelry is not gold.
References and ResourcesFederal Trade Commission: Guides for the Jewelry, Precious Metals, and Pewter Industries
Office of Department of Energy Science Education: Test for Gold