A real gold coin matches its published weight and diameter at the same time, is not attracted to a magnet, and has sharp, correct details with no seam on the edge. Because gold is one of the densest metals in common use, a fake made of brass, copper, lead or plated steel cannot be both the right size and the right weight: it is either too light at the correct diameter or too thick and wide at the correct weight. So the home test that matters most is a scale that reads to 0.01 gram and a cheap set of calipers, checked against the specification for that exact coin. A one-ounce American Gold Eagle weighs 33.93 grams and measures 32.7 millimeters; a British sovereign weighs 7.99 grams at 22.05 millimeters; a $20 Liberty or Saint-Gaudens double eagle weighs 33.44 grams at 34 millimeters. A coin that is off by more than a few hundredths of a gram or a few tenths of a millimeter deserves a professional look before any money changes hands.
With gold at about $4,000 per troy ounce as of late 2026, a genuine one-ounce coin holds about $4,000 of metal, a sovereign about $940 and a double eagle about $3,870, so the stakes are high and the fakes are worth the forger's effort. The reassuring part is that most "gold coins" people bring in are not fakes of real coins at all; they are honestly labeled plated tribute pieces worth a few dollars, and the marks on them say so.
Quick answer
- Weigh and measure. Real gold matches both the published weight and diameter; fakes fail one or the other.
- A magnet must not pull on it. Any attraction means steel or iron underneath.
- Look for the words COPY, REPLICA, "layered" or "clad" and for a seam on the edge. Each one ends the question.
How to check yours, step by step
- Identify the coin exactly. Read the country, denomination, date and design, and find its published specification. Small gold coins of similar size each have their own weight and diameter, and the test only works against the right number.
- Read every word on it. Genuine coins state a denomination, a country or issuing authority and usually a fineness or weight, such as "1 OZ FINE GOLD" or "FYNGOUD 1 OZ FINE GOLD." Tribute coins and replicas say things like "COPY," "REPLICA," "layered in 24K gold," "clad," "proof tribute" or carry no denomination at all. US law requires imitation coins to be marked COPY, and most are, though the word can be small.
- Weigh it to 0.01 gram. Compare with the table below. Genuine gold coins are struck to tight tolerances, within a few hundredths of a gram for small coins and about 0.1 gram for one-ounce coins, and wear removes very little. A coin that weighs 2 to 15 percent light is almost always brass, bronze or a plated base metal.
- Measure the diameter and thickness. Use calipers. A coin of the right weight but the wrong metal has to be bigger to carry that weight, so it will be wider or thicker than the specification, often enough to fail to fit in a coin tube or a Fisch gauge made for the type. Thickness matters because the one metal with gold's density, tungsten, can be hidden inside a thick coin, though it is far more common in bars than in coins.
- Test with a strong magnet. Gold, silver and copper are not magnetic. Hold a neodymium magnet near the coin and slide it slowly; any pull or drag means iron or steel in the alloy or underneath the plating. A coin that ignores the magnet passes this test but is not proven, since brass and tungsten ignore it too.
- Listen to it. Balance the coin on a fingertip and tap it with another coin. Gold has a long, clear, relatively high ring; lead and tungsten-cored fakes sound dull and short; brass sounds brighter and thinner. Treat this as supporting evidence only.
- Examine the details and the edge with a loupe. Struck gold has crisp lettering, sharp denticles and reeding, and fine hair and feather detail. Cast fakes have soft, grainy or pitted surfaces, rounded letters and sometimes tiny bubbles. Look along the edge for a fine seam, which means two halves were joined, and for reeding that is uneven, smeared or stops short of the rim. On plated coins, look at the high points and the edge for a different color showing through.
- Check the color. Pure gold coins such as Maple Leafs are a deep, rich yellow; 22 karat coins such as Eagles and sovereigns are slightly more orange from the copper. A brassy, greenish or pale coin is suspect, and so is one that is too bright and uniform, which often means fresh plating.
Weights and sizes of the gold coins people own most
| Coin | Gold content | Fineness | Weight | Diameter | Melt value, about |
|---|---|---|---|---|---|
| American Gold Eagle, 1 oz | 1.000 oz | 91.67% | 33.93 g | 32.7 mm | $4,000 |
| American Gold Buffalo, 1 oz | 1.000 oz | 99.99% | 31.11 g | 32.7 mm | $4,000 |
| Canadian Maple Leaf, 1 oz | 1.000 oz | 99.99% | 31.11 g | 30.0 mm | $4,000 |
| South African Krugerrand, 1 oz | 1.000 oz | 91.67% | 33.93 g | 32.8 mm | $4,000 |
| US $20 double eagle, 1850 to 1933 | 0.9675 oz | 90% | 33.44 g | 34.0 mm | $3,870 |
| US $10 eagle | 0.4838 oz | 90% | 16.72 g | 27.0 mm | $1,935 |
| US $5 half eagle | 0.2419 oz | 90% | 8.36 g | 21.6 mm | $968 |
| US $2.50 quarter eagle | 0.1209 oz | 90% | 4.18 g | 18.0 mm | $484 |
| British sovereign | 0.2354 oz | 91.67% | 7.99 g | 22.05 mm | $942 |
| Mexican 50 pesos | 1.2057 oz | 90% | 41.67 g | 37.5 mm | $4,823 |
| Swiss 20 francs (Vreneli) | 0.1867 oz | 90% | 6.45 g | 21.0 mm | $747 |
Melt values use gold at about $4,000 per ounce as of late 2026 and move with the market. Bullion coins sell for melt plus a premium of a few percent; older US gold and scarce dates sell for more, as the US gold coins guide and the Krugerrand guide lay out.
What fakes and lookalikes are made of, and what gives them away
| What it is | Weight at correct size | Magnet | Typical tell | Value |
|---|---|---|---|---|
| Gold-plated brass or copper tribute coin | 50 to 60% of spec | No pull | Says COPY, "layered" or "clad"; no denomination; too light | $2 to $10 |
| Gold-plated steel or iron | Light | Strong pull | Magnet settles it instantly | Under $5 |
| Lead alloy with plating | Can be close | No pull | Soft, dull ring; dents easily; grainy details | A few dollars |
| Cast copy in gold or silver alloy | Close to spec | No pull | Pitting, soft letters, edge seam, poor reeding | Metal value only |
| Tungsten core with gold shell | Correct | No pull | Slightly thick; dead sound; fails electronic tester | Shell value only |
| Genuine coin with altered date or mint mark | Correct | No pull | Tooling around the altered digit under a loupe | Value of the common coin |
The first two rows cover the great majority of cases. Most people who ask whether their gold coin is real are holding a tribute coin from a television offer, a souvenir shop piece or a plated replica of a famous coin. These are marked as such and are worth the few dollars of plating and brass they contain. Real counterfeits of real coins are rarer and aimed at the coins with the most value per fake: one-ounce bullion, double eagles and the scarce dates in the older US series.
Common mistakes
- Testing against the wrong specification. A sovereign that weighs 7.99 grams is correct, and so is a half sovereign at 3.99 grams. A one-ounce Eagle at 33.93 grams is correct even though it contains only 31.1 grams of gold, because the balance is copper and silver alloy. Know which coin you have before judging the number.
- Relying on the magnet alone. Brass, copper, lead and tungsten all pass the magnet test. The magnet only catches the cheapest fakes.
- Using a kitchen scale. Scales that read in whole grams cannot tell a 7.99 gram sovereign from an 8.4 gram brass copy. A jeweler's scale reading to 0.01 gram costs very little.
- Scratching or filing a coin to "see the gold underneath." Acid testing and filing damage a genuine coin and lower its value, and plating can be thick enough to pass a shallow scratch anyway. Leave destructive tests to a professional, who rarely needs them.
- Mistaking wear for a fake. A worn double eagle with soft high points and a few dings can still be genuine. Wear is smooth and gradual; casting defects are grainy and random.
- Trusting a holder or the paperwork. Tribute coins come with impressive documents, and real counterfeits come in counterfeit holders. Judge the coin, and check holder serial numbers on the grading company's website.
- Assuming "gold" in the name means gold in the coin. Presidential dollars, Sacagawea dollars and "golden" tokens are brass and contain no gold at all.
What to photograph
- Both faces, straight on, filling the frame. This confirms the type, date and mint mark and shows whether the detail is struck or cast.
- The edge, sharp and well lit. Reeding quality and any seam or color change at the edge are often the clearest sign of a fake, and the edge is also where plated coins show base metal first.
- The scale reading with the coin on the pan. A photo of 33.93 g next to a photo of the coin answers more than any amount of description.
- A caliper reading of the diameter. If you have calipers, this is the second half of the density test.
- A macro of the lettering and the date with light from the side, to show tooling, soft casting or the COPY mark.
How WorthPic reads a gold coin photo
WorthPic runs on the newest and most capable AI model available, tuned for exactly this kind of identification. It reads the legends, denomination, date, mint mark and fineness statement in your photos, compares the design detail and edge against what a struck gold coin of that type should look like, and notes the condition. It gives an honest value range: melt plus the premium the type and condition support for a coin that looks right, or a few dollars for a piece whose own inscriptions say it is plated or a copy. If the edge is out of focus, the scale reading is missing or the mint mark is in shadow, it says that the point is not settled and names the photo that would settle it. WorthPic identifies and estimates. It cannot weigh a coin, test its density or see inside it, so it does not grade or guarantee authenticity. For any gold coin worth more than a few hundred dollars, the step that settles it is a physical check by a coin dealer with an electronic tester, or encapsulation by PCGS or NGC.
When to get it looked at in person
Take a gold coin to a professional when the weight and size are both within specification and the coin is worth more than a few hundred dollars, when it is a scarce date or mint mark whose value depends on it being genuine and unaltered, or when any home test gives an odd result on a coin that otherwise looks right.
- A coin dealer or bullion dealer will check weight, dimensions and usually run an electronic conductivity tester such as a Sigma Metalytics unit, which reads through the surface and catches tungsten and plated cores. Most do this at no charge if you are selling or buying.
- PCGS and NGC authenticate, grade and encapsulate gold coins. Their fees run from tens of dollars for modern bullion to much more for high-value rarities, and the holder is what buyers rely on for older US gold and scarce dates.
If you are sorting inherited gold coins, the how to tell if gold is real guide covers the broader metal tests for jewelry and bars, and the inherited coins guide covers how to work through a mixed collection without losing value along the way.