Broadstruck Coin Errors
What is a broadstruck error?
A broadstrike happens when the coin's retaining collar (the metal ring that constrains the planchet during striking) fails or is missing. Without the collar, the planchet metal flows outward when struck, producing a wider, flatter coin with no clearly defined rim or edge milling. Broadstrike + off-centre is a common combination — a planchet that's misaligned often slips past the collar entirely.
How to spot one
- Coin diameter is larger than standard for the denomination.
- No clear rim — the design fades softly into the edge.
- No edge milling, reeding or inscription — the edge is flat and smooth.
- Weight is normal (no metal loss); only the diameter changes.
Authentication
Genuine broadstrikes show natural metal flow. Hammered or post-mint flattened coins look forced and lack the soft fade-out at the rim.
Famous UK examples
Loses the seven-sided shape because no collar constrained the metal.
Pre-2017 round £1; the bimetal £2 cannot be broadstruck the same way.
Key-date UK coins worth examining
Errors on key-date coins compound rarity — the host coin is already scarce, and the error multiplies the value. Browse the rarest UK coins in our catalogue: