Most gold jewelry is is stamped with a hallmark noting the jewelry's karat weight, such as 10k, 14k, etc. However, not having the hallmark doesn't always mean that the gold is fake. Taking the piece to a reputable jeweler is the only foolproof way to verify whether or not a piece of jewelry is real gold, but there are some tricks you can try at home that can be accurate if done correctly.
Make a light scratch on the piece of jewelry with a small file. Pick a spot on the jewelry that will not be noticeable so you can still have the option to wear it if you should choose. Using a dropper, apply a drop of nitric acid on the scratch you made on the jewelry. If nothing happens, the piece is likely real gold. If you see green, you are likely dealing with a base metal or a gold-plated piece of jewelry. If what you see is a milky substance, then you likely have a piece of jewelry that is gold over sterling silver.
Apply liquid foundation in a small area on your arm. Layer it with powder makeup. Rub the jewelry against the spot. If you see a mark, then likely you have a real gold piece of jewelry. If you see nothing, then the piece is likely fake.
Drop the piece of jewelry in question into a jug almost filled with water. Gold should be heavy. If it sinks, that is a good sign that it could be real gold. If the piece floats, then it is probably fake.
Take your piece of jewelry to a reputable jewelry dealer. They are equipped with testing kits that can determine whether or not the piece is real gold. Some jewelry stores will charge you a small fee for this service, but it is foolproof if that is what you want. Unfortunately, even a jeweler is not going to be able to tell if a piece of jewelry is real gold just by looking at it.
Be wary of people selling jewelry on the streets. Even if it has the hallmark stamp, it is likely fake. If the price is too good to be true, it probably is. There are many jewelry scams. Only a reputable jeweler is going to be able to tell you for certain if the piece is real gold. Some are also able to verify actual karat weight. Unfortunately, in addition to the possibility of being sold a fake, you may be sold a piece that claims to be 10 karat when it is actually seven karat. In the United States, it is illegal to sell it as gold if it is under 10 karat. If you are suspicious, take your piece to a jeweler other than the one that you purchased it from. Call ahead to make sure the jeweler has the equipment to test it.
Things You'll Need
Jug of water