Gold is not a magnetic metal, so if they pull towards the magnet, the beads are fake. However, if they don't react to the magnet, it doesn't necessarily mean they are real, as non-magnetic metals are used in counterfeit pieces as well.
(Fun fact: Real gold is not magnetic.) Fake gold, on the other hand, will stick to the magnet.
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.
Real gold won't be attracted to a magnet while fake pieces made of other types of metals will be magnetic. A heavy gold plating can cause for metals underneath to not be attracted to a magnet, so this method is not 100% accurate.
Fill a cup or bowl with water and carefully drop your gold piece into it. If the gold is real, it will sink to the bottom of the cup. If it's fake, it will float to the top or hover in the middle of the cup.
Like gold, silver is not magnetic. You can use a similar process of placing it in a strong magnetic field to make it slightly magnetic. Knowing that silver is typically not magnetic can help you determine if you have real silver.
By itself gold is not attracted to the magnetic fields we come across in our everyday lives. If you have a massive magnetic field then gold will be ever so slightly magnetic. It's safe to say that for practical purposes gold is not magnetic.
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.
Acid test.
An acid test can reveal the karat of solid gold jewelry, but it can also show whether jewelry is solid gold or gold-plated. With an acid test, a small sample of the jewelry is removed and exposed to acid to induce a color change. The resulting colors indicate which type of metal the jewelry is made of.
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.
Does 18k gold stick to a magnet? It is possible that an 18k gold piece sticks to a magnet. 18k or 18 karat means that a specific alloy contains 75% of pure gold and 25% other metals. Since pure gold is not magnetic, gold itself will not be responsible for the magnetism, but the metal alloyed may be.
Metals such as silver, gold, titanium, platinum, palladium, stainless steel, zinc, pewter, copper, aluminum, and tungsten are not magnetic.
Color of the gold
Pure gold is too malleable to be made into jewelry, so authentic gold chains do not have this bright countenance. Another thing is discoloration. Fake gold jewelry has a very thin layer of gold plated onto it. So if you see an inconsistent color of some part of the jewelry, it could be a fake.
The stamp will typically be on the clasps of jewelry. Some counterfeit gold will have a karat stamp on it, but rarely have a manufacturer's name.
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.
Test with Nitric Acid
Nitric acid will cause damage to fake gold jewelries or turn them green. If your gold chain reacts nothing to the nitric acid, it is a genuine gold.
Any size piece of genuine gold will immediately sink to the bottom of any liquid. Imitation gold floats or hovers above the bottom of the container.
If you put the gold jewellery in a bucket of water and it sinks, then it is made of pure gold. Pure gold is dense and therefore does not float while other metals would float or hover over water.
More commonly counterfeited gold coins are Chinese gold pandas, $20 Liberty Head gold coins and St. Gaudens gold coins.
Fool's gold is actually iron sulfide, a non-magnetic, inexpensive and abundant material that is a byproduct of petroleum production.