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. If that necklace leaps to the magnet, your significant other has some explaining to do.
Pure gold on its own does not magnetize or stick to a magnet. But when about 20% of it is replaced with a metal like iron, it may stick to a magnet or exhibit other magnetic properties. Gold used in jewelry may also be magnetic depending on the alloys used, i.e, the metals combined with gold in the material.
So, unless you are testing a 24 karat gold, do NOT use a magnet to test your 10k, 14k, 18k, etc. gold jewelry because some of the base metals that can be mixed with gold are magnetic so you can get a false read. So testing a gold karat by a magnet is entirely wrong and false.
First off, if your "pure gold" is magnetic, then there is iron inside (or maybe nickel). In fact, this is one way to tell if jewelry is actually gold. If it's not attracted to a magnet then there is no iron - but it still might not be gold. Scammers have been known to coat lead, copper, and aluminum.
Scratch test.
If you cut deep enough that you expose underlying metal, you can assume that it is plated. If it appears to be made of a uniform composition throughout, then it is probably solid 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. If that necklace leaps to the magnet, your significant other has some explaining to do.
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.
First of all, the metals that might be mixed into a fake piece of gold or silver might be non-magnetic materials to begin with. For instance, a gold watch that is combined with traces of stainless steel will be undetectable in the magnet test, because stainless steel itself will not stick to the magnet.
The Skin Test
One of the easiest methods of testing gold purity is the Skin Discoloration Test. Real gold won't leave any stains or spots on your skin. However, if you are wearing fake gold jewelry or handle fake gold bullion - your skin will discolor. Just hold your gold item in your hand for a couple of minutes.
It can still be a low-purity solid gold alloy that contains magnetic metals. 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 bullion doesn't stick to magnets. Gold isn't magnetic, so it doesn't have the ability to be attracted to a magnet. However, a magnet can be used to test if gold is real or not. If the gold isn't attracted to the magnet, it's likely to be real gold.
Why this works: Real gold does not burn or get dark under heat. It simply melts: this is why it can be molded and shaped into different forms without losing its luster and beautiful yellow gold color. On the other hand, other metals like copper, iron, and brass will change color and get darker when exposed to flame.
Gold Isn't Magnetic
If that new “gold” ring is attracted to your most powerful kitchen magnet, it's not real gold. That's not to say that if your piece doesn't cling to the magnet, it's 100% real (silver and other metals also aren't magnetic). The magnet test is simply one way to test for gold content.
Test With Nitric Acid
Make a mark deep enough to scratch through the top layer of gold. Carefully apply a drop of nitric acid to the mark, and determine if the mark turns green or milky. There will be no reaction if the jewelry is either gold or mostly gold.
Vinegar is very destructive, so when you apply the vinegar to a fake piece of gold, the vinegar will cause the jewelry to tarnish. Gold is a non-reactive metal, so real pieces of gold will not react to vinegar.
You will also need a small file or sandpaper to scratch the surface of the gold to be tested. To perform the test, first, scratch a small area of the gold with the file or sandpaper. This will remove the top layer of gold, exposing the inner layer. Next, apply a small drop of nitric acid to the scratched area.
The acid in the vinegar takes a couple of minutes to react with gold and other substances. Keep the vinegar sitting on your gold piece for at least 15 minutes, just to make sure it has gotten enough time to react. Watch the gold for color changes like black or green to see if it is fake.