Determining if a ring or other piece of jewellery is real gold, a base metal or plated metal is rather easy. There are a few simple tests that can be done with little or no preparation, and if those tests still leave one feeling sceptical, there is an acid test that can be performed. The test uses nitric acid, which can be bought at most chemical stores or ordered online, which requires care when handling to prevent burns.
Examine the inside of the ring's band. Jewellers are required to hallmark stamp jewellery made out of precious metals. Gold will have a stamp with the number of carats. Use a bright light because the stamp is often small and difficult to see.
Touch the ring to a magnet. If the ring is attracted to the magnet, it isn't real.
Make a small scratch on the gold with the file. It is best to do this somewhere inconspicuous, like the inside of the band, so that the gold isn't marred in a place that's visible when it is being worn.
Put on the rubber gloves. Drip a drop of nitric acid on the scratch with the toothpick. Watch the reaction closely.
Wash the ring in running water thoroughly. If there was no reaction to the nitric acid, the gold is real. If the reaction is green then it is a base metal, and a milky white reaction signifies silver.
The hallmark stamp test is not guaranteed. Gold produced in some countries has no stamp, and gold produced in Europe uses a number system rather than the carat system. Estate jewellery and other antique pieces will also be blank, and sometimes the hallmark is accidentally cut out when the ring is resized. Some jewellery may be stamped, but is actually a higher quality forgery. High-quality testing kits are available for the very sceptical, but they are expensive. Having a reputable jeweller test the ring is much faster and will cost less.