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.
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.
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.
The most accurate and harmless method in testing gold is using electronic or XRF thermo testing machines.
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.
The acid test (also known as the touchstone test) is the standard for almost all pawnshops and jewelers in the US, it is second to XRF testing (X-Ray Fluorescence testing) which is far more specialist and expensive. XRF machines can cost $20,000 or more, so you can understand why it's not all too common.
Magnet Test
Real gold isn't magnetic, so you will likely see the authenticator using a magnet to see if the jewelry is magnetic. If it moves toward the magnet, that's a clear indicator that the jewelry isn't real gold. Counterfeit jewelry can be made with non-magnetic metals, so there will also be more testing done.
Will gold of different karats stick to a magnet? Gold jewelry, such as 18k gold, 14k gold, 10k gold, and even white gold can be magnetic depending on the alloys, or metals combined with gold, used.
Be sure to use plain white toothpaste; avoid any with colored stripes or other added ingredients. Rub the toothpaste onto the gold for about 30 seconds. You should see a black streak begin to form.
A magnet is all you need to determine if your precious metal piece is brass or gold. Because brass has iron, the magnet sticks due to it iron being a magnetic metal. Gold, on the other hand, is pure and will not move one inch under the influence of any strong magnet.
How to Test If Gold Is Real with a Lighter. The first test is also the easiest test: try to burn your gold. If it's real gold, it will get brighter as you apply the flame but it won't actually catch fire and burn. If your gold piece starts to smoke or gets darker, you likely have imitation gold.
999" or "1.000" would be pure gold and thus the same as 24 karat. Nonetheless, if an item of jewelry does not have this stamp - it is not necessarily proof positive that the item is made from fake gold. This is particularly true of older items of jewelry. Another method how to tell real gold is with a nitric acid test.
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.
Chemistry. Testing for gold with acid focuses on the fact that gold is a noble metal which is resistant to change by corrosion, oxidation, or acid. The acid test for gold is to rub the gold-colored item on black stone, which will leave an easily visible mark.
The white vinegar cleaning solution won't damage your jewelry if it's left in the bowl for more than 20 minutes.
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.
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.
The thin layer of gold is plated onto the base metal to create gold plated jewelry. Since the gold plating is very thin, the gold can rub off easily. It is also more prone to tarnishing when exposed to any kinds of liquids or chemicals.
Take a magnet with you. Iron pyrite will stick to the magnet because of its high iron content; gold will not. You can also use a drop of nitric acid to test your specimen.
Both white gold and yellow gold are high quality metals for your jewelry. However, they do differ significantly in strength. Thanks to its higher content of alloys, white gold jewelry is more resistant to dents, scratches, and damage than yellow gold. For highly active wearers, white gold might be a safer choice.