How to Identify the French Constitutional Ecu

Start with size and metal. The Constitutional Ecu is a large coin, roughly 39-41 mm across and about 29 grams, struck in silver with a decorated or lettered edge. A piece this size that is non-magnetic, rings with a clear silver tone, and shows bright or gently toned metal is consistent with a genuine ecu; a lightweight, magnetic, or greasy-looking piece points to a replica.

Read the obverse. Look for a left-facing bust of Louis XVI with a French legend naming him King of the French (roi des Francois). This wording is a key diagnostic: it distinguishes the Revolutionary constitutional coinage from earlier royal ecus that titled him King of France by divine right. The relief should be sharp and the lettering crisp.

Check the reverse. The reverse shows a standing allegorical figure linked to Liberty and the Genius of France beside fasces, framed by legends invoking the law and the nation, with the value and the date 1792. Confirm the date and legends read cleanly; soft, blurred, or uneven detail is a warning sign of a cast copy.

Locate the mint and rule out look-alikes. Small letters and symbols in the design identify the mint and officials; these matter for attribution and value, so record them carefully. Do not confuse this coin with earlier crowned Louis XVI ecus, later Republican ecus and francs without a royal portrait, or the smaller 3-livres piece, which shares the era but is a different denomination and size.

Authenticate carefully. Weigh and measure the coin against ecu norms, inspect the edge for the correct decoration or lettering, and compare portrait, fasces, and legends with trusted reference images of the 1792 issue. This is a widely copied historical type, so for any valuable example seek third-party grading or a specialist opinion before buying or selling.