Weight and dimensions never lie
Every genuine coin was struck to a published weight, diameter, and thickness within tight tolerances. A digital scale accurate to 0.01 grams and a set of calipers cost little and expose most fakes immediately: counterfeiters using the wrong alloy cannot match weight, diameter, and thickness at the same time.
Look up the official specifications for the exact date and type — compositions changed over time, so a 1964 quarter and a 1965 quarter have different correct weights. A coin more than a few percent off spec deserves deep suspicion.
The magnet test and the ping test
Gold, silver, and copper are not magnetic. If a supposed silver dollar jumps to a magnet, it is fake — full stop. A strong neodymium magnet adds a subtler check: it should slide slowly down a tilted silver or gold surface, dragged by eddy currents, rather than sticking or sliding freely.
The ping test exploits the distinctive ring of precious metal: balance the coin on a fingertip and tap the edge gently with another coin. Silver produces a long, high-pitched ring, while base-metal fakes sound dull and short. Smartphone apps can analyze the ring frequency, though the test is less reliable on small or thick coins.
Visual red flags: seams, fonts, and tooling
Cast counterfeits betray themselves with a grainy or pimply surface, mushy detail, and sometimes a seam line on the edge where mold halves met. Compare the edge reeding to a genuine example — casting rarely reproduces it crisply.
- Wrong or inconsistent letter fonts, especially in the date
- Mint marks that look added, re-punched in the wrong style, or sit at the wrong position
- Tooling marks: fine parallel scratches where a forger re-engraved detail
- Depressions or raised pimples repeated in the fields
- Edge seams, filed rims, or reeding that does not match genuine coins
- Details too soft for the amount of wear the coin shows
Know the high-risk targets
Counterfeiters focus where money is: key dates like the 1893-S Morgan dollar, 1916-D Mercury dime, and 1909-S VDB cent, plus Trade dollars, gold classics, and modern bullion. Altered genuine coins are common too — an added mint mark or a shaved digit turns a common date into a fake rarity.
For any expensive purchase, buy coins already certified by PCGS or NGC, or buy from established dealers who guarantee authenticity for the long term. If a deal on a rare date looks too good, it is.
Add an AI second opinion with CoinVault Pro
CoinVault Pro’s recognition engine combines Gemini AI with Coin-CLIP image matching, comparing your photo against reference imagery to identify the exact type and variety. If the design details, date style, or mint mark placement do not line up with the genuine article, that mismatch is a signal to dig deeper before buying.
Pair the app’s identification and live sold-price data with the physical tests above and you have a solid first line of defense — no lab equipment required.