Wrong Planchet Errors: Wrong Metal, Wrong Size, Big Value

A wrong planchet error occurs when a coin blank intended for one denomination accidentally enters the press for a different denomination. The result is a coin bearing the design of one denomination but on a blank of the wrong size, weight, or composition. Wrong planchet errors are among the rarest and most valuable mint error types because they require a specific, unlikely sequence of events at the mint.

What This Means

Coin blanks for different denominations differ in size, weight, and composition. When blanks from one denomination line get mixed into another, the press strikes them with whatever dies are installed. The resulting coin is the wrong size, wrong weight, or wrong color for its design.

What to Look For

• Coin that is the wrong size for its design (too small or too large)
• Wrong color — a silver-colored coin with a copper design or vice versa
• Weight significantly different from normal for the denomination shown
• Design may be incomplete if struck on a smaller blank
• Design may be spread if struck on a larger blank
• Edge characteristics may not match the denomination

Common Mistakes to Avoid

• Confusing plated or altered coins with genuine wrong planchet errors
• Not weighing the coin — weight is the primary authentication method
• Assuming wrong planchet errors are common — they are genuinely rare
• Confusing foreign coins with wrong planchet errors
• Not getting potentially valuable wrong planchet coins professionally authenticated

What Affects Value

Wrong planchet errors are among the most consistently valuable error types. Value depends on which planchet was used, the denomination of the design, the coin's condition, and collector demand. Professional authentication is especially important for this error type.