How to tell if gold is real: the tests that work and their limits

The short answer

Start with the simple checks: the markings, a magnet, and the item’s weight and size compared with the official specifications. They catch crude fakes made from the wrong metal. The best fakes, made of gold-plated tungsten, can pass all of them, because tungsten is almost exactly as dense as gold. For anything valuable, have a dealer test it with equipment that sees below the surface, such as ultrasound or an electronic tester. Buying from established dealers is still the best protection.

At a glance

Checks you can do at home	Markings, a magnet, weight and size, density
What they catch	Fakes made of the wrong metal, weight or size
What they can miss	Well-made gold-plated tungsten
Tests a dealer can do	Acid, X-ray fluorescence (XRF), electronic testers, ultrasound
Biggest red flag	A price below the value of the metal

Check the markings

Gold jewelry sold in the U.S. is usually stamped with its karat, such as 14K or 18K, or a number such as 585 or 750. The FTC advises looking for the maker’s name or registered trademark next to the karat mark, because that’s the company standing behind it. Marks such as GP (gold plated), GF (gold filled) or RGP (rolled gold plate) mean a layer of gold over another metal. For silver, “sterling” or 925 means 92.5% silver.

Bullion coins carry the mint’s design, the year, the weight and the purity. Bars show the maker, the weight, the purity and often a serial number that matches an assay card. All of these can be copied, so markings are only a first filter.

Try a magnet

Gold and silver aren’t magnetic. A coin or bar that sticks to a magnet is fake, and the Anti-Counterfeiting Educational Foundation lists magnetic coins among the signs of counterfeits sold online.

Passing the test proves little, though. Copper, brass, lead and tungsten don’t stick to a magnet either.

Weigh and measure it

Counterfeit coins are often the wrong weight or size. You need a scale that reads to a hundredth of a gram and a caliper for the diameter. Compare what you get with the mint’s specifications:

Coin (1 oz)	Total weight	Diameter
American Gold Eagle	33.931 g	32.70 mm
Canadian Gold Maple Leaf	31.11 g	30 mm
South African Krugerrand	33.93 g	32.77 mm
Austrian Gold Philharmonic	31.10 g	37 mm
American Silver Eagle	31.103 g	40.60 mm

Figures from the issuing mints. Our coin guides list the other sizes.

The Gold Eagle and Krugerrand weigh more than an ounce because they’re 22-karat gold. Each contains a full ounce of gold plus some copper, and silver in the Eagle’s case. Our guides to the Gold Eagle and Krugerrand explain the alloys.

Check the density

Gold is very dense, so a fake made of a lighter metal has to be either underweight or oversized. A density test catches that even when the weight looks right.

To do it, weigh the item in grams. Then put a cup of water on the scale, zero it, and hang the item from a thread so it’s fully under water without touching the sides or bottom. The new reading, in grams, equals the item’s volume in cubic centimeters. Divide the weight by that number.

Metal	Density (g/cm³)
Gold	19.3
Tungsten	19.3
Lead	11.3
Silver	10.5
Copper	9.0

Pure metals, from the Royal Society of Chemistry’s periodic table. 22-karat coins such as the Gold Eagle come out lower, at roughly 17.6 to 17.8.

The table shows the problem. Tungsten matches gold almost exactly, so a gold-plated tungsten bar or coin can pass a density test as well as a weight check.

Tests a dealer can do

Coin shops, jewelers and refiners have equipment you probably don’t:

Test	What it does	Marks the item?	Sees below the surface?
Acid test	Checks how a scratch on a testing stone reacts to acids	Leaves a small scratch	No
XRF analyzer	Reads the metal’s makeup with X-rays	No	No
Electronic tester	Measures how the metal conducts electricity	No	Some models, to a limited depth
Ultrasound	Sends sound waves through a bar	No	Yes
Fire assay	Melts a sample to measure the gold in it	Yes	Yes

XRF analyzers are accurate, but they only read the surface. A maker of ultrasonic test equipment notes that tungsten inserts are hard to find by eye, by weighing or with radiography, while ultrasound picks up the boundary between the two metals. For a bar you’re unsure about, ask for a test that looks inside it.

The fakes to watch for

Gold-plated tungsten bars. These are the most dangerous fakes because they pass the simple checks. Ask for below-the-surface testing on any bar bought outside an established dealer.
Counterfeit bullion coins sold online. In 2023 the Anti-Counterfeiting Educational Foundation said it had tracked more than 300 websites selling fake coins and bullion, with American Silver Eagles among the targets. It warned that “the quality of many counterfeits is quite good and easily can deceive buyers.”
Fake certificates and holders. Assay cards and coin grading holders can be copied too. For graded coins, look up the certification number on the grading service’s website.
Plated jewelry sold as solid gold. Check the marks, and be wary of “solid gold” pieces priced like costume jewelry.

How to avoid buying a fake

Buy from established dealers with a track record and a physical address. The foundation’s advice is blunt: “if you don’t know precious metals or rare coins, you’d better know a reputable seller.”
Walk away from prices below the value of the metal. Nobody sells real gold at a loss.
Keep coins and bars in their original packaging, and check that serial numbers match any assay card.
For a private sale, meet at a coin shop and have the item tested before you pay.

Our guide to red flags when buying gold covers the sales tactics, and buying gold locally explains how to check a shop.

If you think you have a fake

Stop using or reselling the item. Contact the seller and, if you paid by card or through a marketplace, your card issuer or the platform, which may be able to reverse the payment. You can report counterfeit coins and bullion to the Anti-Counterfeiting Educational Foundation and fraud to the FTC at ReportFraud.ftc.gov.

Frequently asked questions

Does real gold stick to a magnet?

No. Neither gold nor silver is magnetic, so a coin or bar that sticks is fake. Passing the test proves little, because copper, brass, lead and tungsten don’t stick either.

Can a gold-plated tungsten bar pass a weight test?

Yes. Tungsten is almost exactly as dense as gold, so a well-made fake can have the right weight and size. Ultrasound or an electronic tester that reads below the surface is needed to find it.

Is a dealer’s XRF test enough?

For coins and jewelry it’s a good check of the metal at the surface. For a bar, it can’t see a tungsten core, so ask for ultrasound or another test that reads inside the bar.

Can I trust a coin in a grading-service holder?

Usually, but holders have been counterfeited. Look up the certification number on the grading service’s website and check that the coin matches the listing.