As a refinery, we deal with high volumes of gold in all manner of shapes, weights, and purity levels. We’re able to leverage several types of assays to authenticate the melt-value of anything a customer may bring us. However, if you plan on purchasing gold, the types of assay equipment we’d recommend may not be available. Fortunately, there are several quick and easy ways to catch fake gold before you commit to a purchase.
Discoloration: Pure gold does not tarnish, so carefully check for any discoloration. Even slight shade variations can reveal fake gold.
Magnets: Gold (and other precious metals) are not magnetic. If the piece in question reacts to the magnet, it can only mean two things: 1) the piece is completely fake, or 2) the piece contains a lot of magnetic impurities (such as nickel or tungsten) and may be a lower karat than advertised. Make sure to use something stronger than a refrigerator magnet.
Scratching: Even without acid, a simple scratch test is enough to uncover many types of fake gold. Most counterfeiters don’t have the time or resources to plate a counterfeit thicker than what a scratch can uncover. The streak left behind by a scratch can also tell you something. For example, fool’s gold will leave behind a greenish grey streak, but gold will leave a shiny and bright streak of yellow. For best results, scratch against basalt or unglazed ceramic.
Float test: Check the buoyancy of the item by dropping it in a glass of water. Real gold is dense and will sink, but many counterfeits will float. Of course, this test is more effective on small samples, such as jewelry or alluvial flakes. Be aware that many metals designed to look like gold are still dense enough to sink, so even if the piece passes the float test, you should still try additional assays.