Scrape a small piece of your gold ring with a file. Scratch an area that is not often seen, such as on the inside of the ring. Apply one drop of nitric acid on the spot and take note of what happens. If the area turns green, you've got a phony on your hands. If the spot turns milky-white, your piece is probably made of sterling silver with gold plating over the top. If nothing happens, your fabulous gold is authentic.
Compare the weight of a real piece of gold with your questionable piece. Find an authentic gold ring that is the same size as the ring you are suspicious of, and place them on a balance scale. Gold is relatively heavy, and if the scale stays about the same when both pieces are weighed, your gold is likely real. If the known real gold is heavier than the other piece, you probably have an impostor.
Hold a magnet up to the piece in question. If the gold is fake and made of metal, it will likely stick to the magnet. If the gold is real, the magnet will have no effect on the piece of jewelry.
Rub your ring against a slab of unglazed ceramic, as long as you don't mind inflicting a small amount of scratching on the jewelry. Look at what color mark the piece created. A gold mark is indicative of authentic gold. A black mark is the sign of a phony.
A certified jeweler can tell you whether your ring is real gold. If you've performed the tests or don't want to risk harming your jewelry, take it to a jeweler for testing.
Any gold that is under 10 karats isn't considered genuine gold in the United States. In general, gold rings that are 10 karats or less contain less than 42 percent of real gold.
Be wary of purchasing gold from dealers advertising "discount" or "blowout" prices, as they may not be selling genuine gold.