How to Tell Whether an Ancient Coin Is Genuine

Forgeries of ancient coins are as old as the coins themselves. Plated “fourrée” denarii were passed in Roman markets two thousand years ago. Today the problem is modern: cast copies sold as souvenirs, and skilled die-struck fakes made to deceive collectors. After three decades in the trade, here is how we judge whether an ancient coin is genuine, and what you can check yourself before you buy.

1. Weight and size

Ancient mints struck to weight standards, and genuine coins fall within known ranges. An Attic-standard tetradrachm weighs about 17 grams. A late Roman or Byzantine gold solidus weighs about 4.4 to 4.5 grams. An early imperial Roman denarius weighs roughly 3.4 to 3.8 grams.

A coin far outside its range deserves a second look. Cast copies are often light, because metal shrinks as it cools in a mould. A good digital scale accurate to 0.01 g is the most useful tool a collector can own. Compare your reading with the weight given in the standard reference for that type.

2. Signs of casting

Most fakes on the market are cast from a genuine coin. Casting leaves telltale marks:

• Soft, rounded detail. Letters and hair lose the crisp edges a die leaves.
• Tiny pits or bubbles in the fields, especially near the rim.
• A seam on the edge, often filed away, leaving file marks or an unnaturally smooth edge.
• A grainy surface under magnification where a struck coin would show smooth, flowing metal.

A 10x loupe shows most of these in seconds.

3. Struck forgeries: the harder test

Struck fakes are made with engraved dies, so they show no casting marks. They are the reason experience matters. The giveaways are usually in the style:

• Portraits that look slightly modern, too neat, or wrong for the mint and period.
• Letter forms that do not match the genuine dies of the type.
• Flans that are too round, too uniform, or have a modern-looking edge.
• Many “different” coins sharing the same dies and the same flaws, offered by several sellers at once.

Specialists compare suspect coins against known genuine dies and against published forgery reports. Collectors can do the same with online fake-report databases and auction archives.

4. Surfaces, patina and deposits

Two thousand years in the ground leaves a natural record. Silver tones in soft grey, blue and gold. Bronze develops a patina that is part of the metal surface, often with earthen deposits sitting in the recesses.

Artificial patinas tend to be uniform, glossy or chalky, and sometimes flake to reveal bright metal below. Deposits glued on to hide casting marks can sit on top of the design rather than in the low areas. On gold, which does not corrode, be wary of pieces that look worn yet show casting texture.

5. Provenance and the seller

The most reliable protection is who you buy from. A coin with a documented history, from a named collection or a published auction, carries far less risk. Ask how long the seller has dealt in ancient coins, whether they belong to recognized numismatic organizations, and what happens if a coin is ever shown to be false.

Be cautious of prices that are too good to be true, especially for gold, famous types such as the “Eid Mar” or the Judaean shekel, and coins of rare rulers. Those are exactly the coins forgers make.

6. Third-party grading

Independent services such as NGC Ancients examine coins and encapsulate them with a grade. Certification adds confidence, particularly for higher-value pieces, and many of the coins in our collection carry NGC certification. It does not replace knowledge, but it is a sensible second opinion.

How we guarantee what we sell

Palmyra Heritage Gallery has dealt in ancient coins in New York since 1995. Every coin we offer is examined in hand, weighed, photographed in high resolution and described in full, and every piece is guaranteed authentic. We are members of the American Numismatic Association, the American Numismatic Society and the Florida Numismatic Association.

If you have a coin you are unsure about, or one you are thinking of buying elsewhere, get in touch. We are always glad to talk coins.