Blank planchets, although strictly speaking aren't error coins, are still collected by error
coin collectors. They are coin planchets produced at the mint to become coins but
somehow didn't quite make it to the die's to be pressed.
There are two types of blank planchets:
Type 1 - Planchets which have just been produced and are newly cut.
Type 2 - Planchets which have been cut and then been through the next stage
(softening process) which then display rims.
Victoria Old Head Halfpenny Blank Planchet (type 2)
Hus Sulo Collection