Gold is a very soft metal, so scratching it with a hard object like ceramic will leave a golden or a yellowish streak. On the other hand, fake gold is often made of metals that are darker in color, so you'll see a dark streak instead.
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.
Drop the Item in Water
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.
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.
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.
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.
Float Test
It is one of the easiest ways of checking gold purity at home. 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.
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.
Q: HOW LONG CAN YOU LEAVE GOLD IN VINEGAR? A: When you clean jewelry with vinegar, you can submerge your gold jewelry in the vinegar solution for up to 20 minutes, but it's best not to go beyond that point.
Lemon Juice
Lemon is naturally acidic, which helps remove the oxide layer on the jewelry easily. Mix equal parts of water and lemon juice. Soak the jewelry in this solution for 10 to 15 minutes. Gently scrub the jewelry with a rough cloth or toothbrush.
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.
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.
Gold is classified as a heavy metal despite its softness and malleability because each of its atoms is heavy on its own. It is a dense material.
In a nitric acid test, a jeweler places a few drops of the acid on the piece and watches the reaction. With copper, the reaction usually causes the liquid to turn green, give off fumes, and sometimes bubble. This response is known as a hard cupric reaction and indicates that your piece is not real gold.
More commonly counterfeited gold coins are Chinese gold pandas, $20 Liberty Head gold coins and St. Gaudens gold coins.
Popular copper alloys (bronze and brass), are the most common type of counterfeits out there. Between them, brass (copper-zinc alloy) has a wider use case for imitation gold because of retaining its gold-like color for longer than bronze (copper-tin alloy).
Not sure if your gold is real or fake? It's simple: Solid gold never tarnishes, while faux gold—or gold-plated metal—does. If your jewelry has started to discolor and tarnish, or if it turns your skin blue or green where it comes in contact, then it's not solid gold.
Toothpaste can damage your diamonds, gemstones, gold and silver. Toothpaste is abrasive and has a hardness of around 3/4 on the Mohs Scale of Hardness. Metals such as gold and silver are softer, so toothpaste can actually scratch damage your gold and silver jewellery.