Introduction to Error Coins: Types and Terminology

What Are Error Coins?

Error coins are coins that deviate from the intended design or specifications due to mistakes during the minting process. They are genuine US Mint products — not counterfeits — that slipped through quality control. Many are valuable collectibles.

Three Categories of Errors

1. Planchet Errors

Errors in the blank metal disc before striking:

• Wrong planchet — Coin struck on a planchet intended for a different denomination.
• Clipped planchet — Part of the blank was cut away by the blanking press.
• Lamination error — Flaking or peeling metal from impurities in the alloy.
• Off-metal — Struck on the wrong metal composition.

2. Die Errors

Errors in the dies used to strike coins:

• Doubled die — Design elements appear doubled from a misaligned hub impression.
• Repunched mint mark (RPM) — Mint mark punched more than once in slightly different positions.
• Overdate — One date digit punched over another.
• Die crack/cud — Cracks in the die create raised lines on the coin.

3. Striking Errors

Errors during the actual striking process:

• Off-center strike — The planchet was not properly centered between the dies.
• Broadstrike — Struck without the collar that forms the edge.
• Double strike — Struck twice, with the second strike offset.
• Brockage — A previously struck coin remained in the press and impressed its design into the next coin.

What Makes Error Coins Valuable?

• Dramatic visual impact — The more obvious and dramatic the error, the more valuable.
• Rarity — Fewer surviving examples = higher value.
• Denomination — Errors on silver dollars are worth more than errors on cents.
• Eye appeal — A 50% off-center cent showing the full date is more desirable than a 10% off-center.

Up Next

Doubled Dies: How They Happen and Which Are Valuable.