Acid tests have a relatively high tolerance. In other words, they are a good rough estimator of gold using the Karat scale, and even then, you shouldn't rely on it to the decimal point. Simply put, acid testing isn't always the most accurate.
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.
Any trader who buys gold regularly will use up the acid long before the use-by date. Acids will last until at least the use-by date if stored correctly.
The Magnet Test
However, some of the base metals that can be mixed with gold are also non-magnetic so you can get a false read. The test isn't foolproof so it's a good idea to do this in conjunction with another more accurate testing method.
How to Test Gold With Vinegar. 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.
Acid tests have a relatively high tolerance. In other words, they are a good rough estimator of gold using the Karat scale, and even then, you shouldn't rely on it to the decimal point. Simply put, acid testing isn't always the most accurate.
The most trustworthy method to test if something is gold plated or solid gold is to have an acid test done it. For the acid test, take a small piece of jewelry, or using a small needle scratch a tiny part in your gold, take a dropper given in the acid kit, fill it with acid.
Heat your gold jewelry with the lighter.
Apply the flame to the jewelry for about a minute or 60 seconds. Watch it closely for any changes in color. Fake gold will get darker, while pure gold will do the opposite: it will get brighter the hotter it gets.
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.
The gold testing machine is almost 100 % accurate with a variance of +_ 0.1%.
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.
A float test using water is the easiest and safest way to tell if your gold is real at home. Start the process by taking a glass and filling it with water. Drop the gold accessory you want to test in the filled glass. If your gold piece sinks to the bottom of the glass, it is real.
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.
The apple cider vinegar gold test is a great choice if you want to test your jewelry at home, as it is readily available and easy to do. After all, real gold will not react when exposed to the acids in vinegar, toothpaste and more.
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.
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.
Acid-Test Ratio FAQ
It is calculated by dividing the sum of a company's cash, cash equivalents and marketable securities by its total current liabilities. The higher the acid-test ratio, the better.
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.
Goldmeter - real gold detector on the App Store.
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.