Double Die
Example(s)
Penny 1952
Description
Double die (or hub doubling) coins present a clear doubling on numbers, on letters and/or occasionally on the main design. The doubling was already on the die before the striking process.
Explanations
It is caused by a misalignment or mismatch between the hub and the die which happens during the hubbing process, i.e. when the design on the hub is transferred by die sinking or annealing. This metal working process is used to softened the die and help the impression on it. Double die occurs between the first and subsequent hubbing.
The doubling from a double die is marked by a clear doubling and all coins struck from a double die will show the same degree of doubling from coin to coin. On a die deterioration, the doubling is undefined, rough and of different width with subsequent strikes.
