The Float Test All you need is a cup (or bowl) of water and your gold item. Place your gold piece into the water. If it's genuine gold, then it will immediately sink to the bottom of the cup. Pure gold is heavy due to its high density – 19.32 g/ ml.
Apply a few drops of white vinegar to your gold jewelry. Real gold will not change color, but vinegar can cause fake gold items to react and change color.
Gently drop your gold item into the water. Real gold is a heavy metal and will not float, so if your gold item floats you know it is not real gold. Also, if you notice rust or tarnishing on the item after being in water, this is also a sign it is not real gold since gold doesn't rust or tarnish.
Set your jewelry or gold piece onto a flat surface. Use an eyedropper to apply a bit of vinegar and let it sit for about 15 minutes. Real gold won't change color, but fake gold will. You can also submerge the gold in a glass container with vinegar for 15 minutes.
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.
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.
Goldmeter - real gold detector on the App Store.
Solid gold chains are made entirely from a gold alloy and will be stamped with a purity mark. Gold plated or gold filled chains, on the other hand, have a base metal like brass that has been covered in a thin layer of actual gold alloy.
What does it tell you if those "pure gold" earrings are attracted to a magnet? 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.
Since gold is both paramagnetic and diamagnetic, both cancel one another out and become weak. So a strong magnet will attract gold ever so slightly and will also repel it.
Pure gold on its own cannot stick to a magnet. However, if you have an alloy of gold, then it could stick to a magnet. An example of a gold alloy that may stick to a magnet is gold with over 20% of its atoms replaced by iron. In very cold temperatures this alloy of gold may magnetize all on its own.
Genuine gold will stand up to your attempt to conduct a nitric acid test at home. Make a tiny mark on the piece of gold to penetrate the surface. Drop a small amount of liquid nitric acid on that scratch and wait for a chemical reaction. Fake gold will immediately turn green where the acid is.
Fool's Gold can be one of three minerals. The most common mineral mistaken for gold is pyrite. Chalcopyrite may also appear gold-like, and weathered mica can mimic gold as well.
While brass is not bright yellow, it's more dull than gold. However, gold is much shinier causing its golden color. Impurities can cause the shiny metallic luster that is characteristic of gold to fade. The purity of the gold determines the shine of ornaments.
Vinegar Test
Once you have some vinegar, clean your piece of jewelry with a rag or cloth to remove any dirt so you don't get faulty results. Then, place your jewelry into a bowl and add a few drops of your vinegar into the bowl. Real gold will not change color, but fake gold will turn either black or green.
The purer the gold, the stronger the acid required to dissolve it. Measured strengths of nitric acid are used to test for 14k and lower. Aqua regia, a mixture of one part nitric acid and three parts hydrochloric acid, is used to test higher karat purity through the process of comparison and elimination.