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. Observe the reaction, and compare the results to the chart provided in the kit.
Test Gold Using the Float Test
Take a cup or glass, fill it up with water, now bring the gold that you want to test. Drop it into this filled glass. If the gold floats, it is surely not real but if the gold sinks to the end of the glass then it is pure gold. The real gold will sink due to being a heavy metal.
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.
One of the most foolproof methods for testing your gold jewelry is the ceramic scratch test. For this method, get an unglazed ceramic plate or piece of tiles and scrape a piece of gold across the surface. Real gold will leave a gold-colored marking, which other metals will just leave a black streak.
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.
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. Gold-over-sterling silver will become milky in appearance. Gold will not react to the nitric acid.
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.
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.
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.
There are over seven tests you can choose from when testing gold at home. These include the magnifying glass test, hallmark test, skin test, float test, the magnet test, and acid test. You can also learn how to tell if gold is real with makeup, and how to test gold at home with makeup.
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.
One study showed that when a 14K white gold ring was placed in common household bleach for 36 hours, the ring completely disintegrated! Small amounts of chlorine exist in tap water, too.
Fake Jewelry or Plated Jewelry Turns Your Skin Green
Over time, even the most robust metals will wear down. If your jewelry is silver or gold plated, the plating will wear down and expose the cheaper metal underneath. Your skin will react to the cheaper metal, most likely copper, and leave a green stain.
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.
Basically, gold won't react to nitric acid, but all other metals will turn greenish. Don't douse your jewelry in the acid—just put it in a stainless-steel dish and use a dropper to drop or Q-tip to test a tiny section. If your jewel doesn't react to the nitric acid, you have a real gold piece (14k or higher).
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.
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.
Heat your gold jewelry with the lighter.
Fake gold will get darker, while pure gold will do the opposite: it will get brighter the hotter it gets. The brighter your jewelry gets, you can rest assured you have real gold.