Five Checks That Catch Most Counterfeit Coins

Counterfeiting is the oldest profession in numismatics — some fakes in the market are themselves centuries old. Modern buyers face everything from cast souvenirs to laser-engraved dies. These five checks catch most of them.

1. Weight and dimensions

Every catalogued coin has a published weight and diameter. A digital scale reading to 0.01g and a caliper are the cheapest insurance in the hobby. Cast fakes are usually light; plated fakes are usually wrong in diameter or thickness. Genuine tolerance is tight — a silver rupee more than 2% off standard weight deserves deep suspicion.

2. The edge

Edges are hard to fake and easy to check. Look for the correct milling, lettering, or security edge for the type. Cast counterfeits often show a seam line along the edge where the mould halves met — under 10x magnification it is unmistakable.

3. Strike character

Struck coins have flow lines — microscopic radial lines from metal flowing under die pressure — and crisp, slightly rounded relief. Cast fakes show pitting, a greasy surface texture, and soft detail in the deepest parts of the design, exactly where a strike is strongest.

4. Surface and tone

Natural toning accumulates in protected areas first and follows the metal's chemistry. Artificial toning — applied to hide cleaning or casting — sits on top of the surface, often in implausible rainbow bands. Original surfaces under magnification look like skin; doctored surfaces look like paint.

5. Provenance and price

The final check is economic: rare coins do not sell cheap. A bargain example of a famous rarity from an unknown seller is a counterfeit until proven otherwise. Provenance — an old collection, a named auction, a certificate — is worth paying for because it transfers the authentication burden to history.

When any check fails, walk away or demand certification. On TNH, every item carries a lifetime authenticity guarantee — but these habits will serve you everywhere else.