PART IV. Die Errors:

Collar Cuds: 

Complete Collar Break

Definition: Here an entire segment of the collar’s working face (or hardened lining) breaks away, leaving a void that begins and ends quite abruptly. A key diagnostic for a full collar break is a “step-up” at both endpoints. The step marks the transition from the normal portion of the edge that shows collar contact to the area where coin metal was free to expand.

This 2000-D nickel depicted below is a stellar example of a complete collar break. About 100 arc degrees broke away, allowing the coin metal to flow into the resulting void. Both die faces show heavy die damage. The damage could be from fragments of the collar, or could indicate that both the collar and the dies were damaged by foreign matter that entered the striking chamber. Another sweet bonus is the small second strike that interrupts smooth convexity of the collar break at 1:00.

Because the gap in the collar was considerably smaller than 180 degrees, the planchet had no choice but to settle against the intact side of the collar. But this is not always the case, especially when the gap in the collar equals or exceeds 180 degrees

Left end of the collar break.

                         Right end of the collar break.