Acid testing for gold is a good initial indicator and rough estimator of purity, especially for identifying obvious fakes, but it's not perfectly accurate and can be fooled by sophisticated counterfeits like tungsten-filled bars or thick plating, so professional verification often uses more advanced methods like XRF analysis for definitive results. It works by using nitric acid to see if the metal dissolves or changes color, with pure gold resisting the acid, but it struggles with very close karat distinctions or internal counterfeiting.
Although results are considered reliable for the most part, there are several reasons to stay away from the acid and choose a Thermo Scientific™ Niton™ handheld analyzer instead. Acid does not give you an exact Karat count.
An immediate reaction to the acid indicates the gold has low purity. A green reaction indicates the item is a base metal or is gold-plated. A cream or milk-colored reaction indicates the item is gold-plated sterling silver. If there is no reaction, the item has high purity or is pure gold.
The Nitric Acid Test
The acid will dissolve any base metals that aren't real gold. If the mark remains, apply nitrohydrochloric acid, also called aqua regia (75% nitric acid and 25% hydrochloric acid) to the mark. This mixture dissolves gold so, if the mark disappears, the gold is real.
XRF Testing
X-rays are emitted into a metal via an XRF analyzer, which measures the energy released by the excited electrons to determine the sample's composition. Results from this quick and easy test are provided in seconds, and XRF analyzers are widely regarded as the most reliable tools for metal testing.
To perform the test, place your gold item into a small bowl and add a few drops of white vinegar. Pure gold will not react or change color because it's non-reactive. Fake or low-quality gold, however, may turn black or green.
Gold is highly malleable in its purest form, which is why it is mixed with other metals like zinc, nickel and other alloys to increase its durability and strength. 999 is the purest form of gold, meaning it has 99.9% gold whereas 916 has 91.6% gold.
Vinegar Testing
You'll only need the piece of jewellery in question and some white vinegar. You can tell if a piece of jewellery is pure gold by placing it on a table or in your palm and pouring white vinegar straight onto the metal. If the metal of the jewellery changes colour, it is not pure gold.
For example, exposure to strong acids, such as hydrochloric acid, can dissolve gold and cause it to be destroyed. Similarly, exposure to strong bases, such as sodium hydroxide, can cause gold to corrode and become damaged. In addition to chemical reactions, gold can be damaged by physical forces.
Pure gold is slightly reddish yellow in color, but colored gold can come in a variety of different colors by alloying it with different elements. Colored golds can be classified in three groups: Alloys with silver and copper in various proportions, producing white, yellow, green and red golds.
In many parts of the world—especially in India, the Middle East, and Southeast Asia—22K gold is the gold standard for wedding and ceremonial jewelry. It contains fewer alloy metals than 18K or 14K gold, so the yellow is more vibrant and traditional.
If you can, wait overnight. This will ensure that the acid has had sufficient time to completely dissolve the gold.
Next, put on protective gloves and place a drop of acid from the 18k gold testing bottle over the small notch. A highly effervescent green reaction indicates base metal, and no further testing is required. If there is little or no reaction, the piece is likely karat gold, and the next test is for purity.
Discoloration: Genuine gold will not change color or show signs of fading or tarnishing. Counterfeit gold may, however, exhibit discoloration, turning green or black due to a chemical reaction with the lighter flame.
Home Tests that Worked
As of January 9, 2026 at 07:25 PM ET, the live Gold spot price for 1 ounce of Gold in U.S. dollars (USD) is $4,523.73, 1 gram of Gold is $145.44 and 1 kilogram of Gold is $145,441.30.
999 gold consistently costs more per gram than 916 gold because of its higher purity. Bullion rates (market prices) are usually lower than retail jewellery prices, especially for simple bars and coins, which have minimal making charges.
Pure gold (24K) has the highest resale value, while lower karat gold (e.g., 10K) contains more alloy metals and is worth less. If you're selling gold jewelry, look for a stamp indicating its karat rating or consult a professional to test the purity.
Rare Earth Magnets
Your first line of defense when testing gold should be a good rare earth magnet. Using this highly affordable and readily available tool allows you to quickly identify non-gold items in a large gold scrap lot or when testing a single item.
Real Gold Always Sinks in Water
While solid gold typically sinks, thin gold pieces or jewelry with a hollow core might float or hover just below the surface. So, while gold has a high density, this test can still be misleading for certain pieces.
Real gold doesn't burn or get darker when heat is applied. If the piece of gold is real, the heat will melt the gold which is why gold can be molded and formed into different shapes without losing its color. Other metals like copper, iron, and brass change color and get darker when it is exposed to heat.