Die fragments of significant size almost always break off at the sharp junction where the die face meets the die neck. Hobbyists refer to such die breaks as “cuds.”
Cuds vary enormously in shape. Most can be characterized as “ovoid,” with the understanding that these can range from squat to tall, as viewed face-on. A less common type of cud occurs when a long, curved sliver separates from the edge of the die face. An example of such a “crescentic cud” is seen on the obverse face of a 1979 Argentina 100-peso coin. It accounts for approximately 160 arc degrees of the coin’s perimeter. A conventional ovoid cud occupies the opposite pole.
Ovoid cuds can be transformed into irregular-looking crescentic cuds as metal continues to break off from the ends of the original void in the die face. Shown here is 1982 Lincoln cent with a thick crescentic cud that represents the culmination of a three-stage cud progression that began as a relatively squat ovoid cud (see the Aug. 9, 2010, column).
Connect with Coin World:
Several crescentic cuds can link up end-to-end to encircle or nearly encircle the die face. Only a few examples of these “circumferential” or “360 degree” cuds are known. Shown here is a 1975 Mexico 1-peso coin with a circumferential cud on the obverse face that appears to represent the merger of three to four crescentic cuds. A very similar circumferential cud appears on a 1961 New Zealand penny (not shown). A nearly complete (355 degree) cud appears on the obverse face of a 1917 Serbia 20-para piece (see photo). Perhaps as many as six contiguous crescentic cuds contributed to this die’s broken perimeter.
Crescentic and circumferential cuds are symptomatic of a brittle exterior separated from a tougher interior by a narrow zone of weakness. This uneven fragility can be caused by improper die preparation (annealing, tempering, quenching). The wrong temperatures applied for the wrong amount of time can create a nonuniform atomic and crystalline micro-structure that is prone to failure.
In a circumferential cud, you would expect the remaining design to be especially well-struck, since the full force of the strike is concentrated in a smaller area. But the center of the 1-peso coin is poorly struck on both faces and bulges out on the obverse.
The bifacial weakness and obverse convexity show that the obverse (hammer) die suffered from a die subsidence error. The retreating center of the obverse die neck was abnormally soft and malleable, in stark contrast to the brittle exterior.