Because gold is expensive, some people try to defraud the public by selling them fake gold or gold that has been bonded over another metal. Some of these fakes look real, have the weight of real gold and wear like gold--at least until the plating wears away. To protect yourself against these "pretenders," it is important to know how to tell if a gold chain is real.
Look for markings on the gold. By U.S. law, real gold is required to be marked as "10K," "14K," "18K" or "24K," which represents its purity. However, if the chain is purchased outside of the United States, such markings may not exist.
Ask a jeweller, who can examine and test the metal for its authenticity. Most generally do not charge for this service.
Look around the chain's clasp with a magnifying glass. Gold plating does not always adhere well around tiny "O" rings that hold the chain to the clasp. Sometimes it is possible to see a darkening of this area with the naked eye. If the area is green or black, the chain is not real gold.
Wear the chain for a while, and if it turns your skin green, it isn't real. If your body chemistry changes the colour of the gold to brown, green or black, it isn't real gold.
Handle the gold chain. Gold is soft; the more pure the gold, the softer it is. Fake gold, on the other hand, typically has stronger metals underneath and isn't easily stretched, bent or dented. Dealers still check for fake gold coins the old fashioned way--by biting them. If they don't dent, they are likely not real.
Clean your gold chain. Fake gold will not clean properly. It will look streaked or will not clean at all. It may even turn green, brown or black in strong jewellery cleaners.
Purchase gold chains only from reputable jewellers. Always ask the jeweller if it's real. No reputable dealer will be offended.
Never assume the chain's authenticity. Avoid pawn shops, street dealers, and dealers that sell under the table.