What to do: Hold the magnet up to the gold. If it's real gold it will not stick to the magnet. (Fun fact: Real gold is not magnetic.) Fake gold, on the other hand, will stick to the magnet.
Check if your gold is real by performing the magnet test. Real gold will not attract a magnet. To test if 18k gold is real, hold it next to a magnet. If the magnet sticks to your jewelry, then it does not have a high percentage of gold but is made up of other, more magnetic metals.
In their pure, natural forms, gold, silver, aluminum, copper, brass, and lead are not magnetic. This is because they are all weak metals.
As we have mentioned above, pure gold is not magnetic. Therefore, 24-karat gold jewelry will not be attracted to magnets. On the other hand, gold alloys that contain iron, cobalt, or nickel can be magnetic. It is not the gold that is creating magnetism.
Gold is a noble metal which is resistant to change by corrosion, oxidation, or acid. You can rub the gold-colored item on jeweller's black stone, which will leave an easily visible mark. The mark is tested by applying nitric acid and hydrochloric acid, which dissolves the mark of any item that is not gold.
If the piece is real gold, the stamp should bear a manufacturer's mark and a karat marking, such as 14K or 24K. Fake gold may bear a karat mark, but will not have a manufacturer's mark.
A single atom of gold has an odd number of electrons, so it will always have one unpaired electron. But in bulk, these unpaired electrons can be shared between atoms, allowing them to find a buddy and form a pair. This means that metallic gold has no unpaired electrons, and it does not display classical magnetism.
20k gold is comprised of 20 parts pure gold and 4 parts other alloys. This is equivalent to 83.3% gold and 16.7% alloy. As it is quite rare, this type of gold karat is not often seen on the current market, but can sometimes be found in antique jewelry.
22-carat gold is also called 916 gold as it contains pure gold with a percentage of 91.67%. Due to the metal composition, the remaining portion is of other mixed metals to make it more durable. The price of 22-carat gold is lower than that of 24-carat gold in the domestic and international markets.
Yes, 10 karat yellow gold is considered real gold because it has 41.7% pure gold in its mixture. The 10k gold meaning is that it contains 10 parts gold and 14 parts alloys and other mixed metals. Typically, 58.3% of 10k gold is made up of alloys and mixed metals.
Fool's gold is actually iron sulfide, a non-magnetic, inexpensive and abundant material that is a byproduct of petroleum production.
On the other hand, a piece may be gold plated, but it will not attach to a magnet because its core metal is non-magnetic.
Natural Diamonds are magnetically inert (diamagnetic). They can be imitated by natural Zircon, and by many man-made materials such as Moissanite, Strontium Titanate and synthetic Rutile (all diamagnetic).
Look for Stamps or Hallmarks in Your Gold Jewelry
Most real gold is stamped with a hallmark that indicates its purity, aka its karat. The karat is the unit used to measure the purity of gold. The higher the karat, the purer the gold. The most common karats you'll see are 10k, 14k, 18k, 22K, and 24k.
Because pure gold is denser than other metals, a gold item will sink quickly and directly to the bottom of a tub or bottle of water. Fake gold can float or fall more slowly. Real gold also won't rust or tarnish when exposed to water, while gold plated items can show discoloration.
Place your jewelry on a table or hold it in your hand, pour some white vinegar on the metal directly (a dropper can also be used) if the metal of the jewelry changes its color, it is not pure gold and if it keeps shining then you have real gold in your hand.
The Magnet Test
Since gold is not a magnetic metal, your jewelry should remain unaffected. If it sticks to the magnet, it's fake. (This test also works with silver, another non-magnetic precious metal.)
Goldmeter - real gold detector on the App Store.
If your gold piece turns black or green when the vinegar is on it, or if it starts to smoke or fizzle at all when the vinegar touches it, it is most likely not real gold. If your gold piece does not change colors and does not fizzle or react to the vinegar in any way, it is probably real.