Error Coin Essentials: Die Breaks

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Error Coin Essentials introduces the core concepts behind coins that didn’t come out quite right. These articles provide a practical foundation for collectors who want to understand how errors happen, how to identify them, and how to collect them. With strong collector demand and wide variety, error coins remain one of the hobby’s most engaging fields. 

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One of the more common forms of brittle die failure is the die break. Referred to as a “piece-out” by mint employees, a die break occurs when a piece of steel breaks free of the die face, leaving a void into which coin metal flows. If the break is large enough, coin metal withdraws from the opposite die, forming a diagnostic hollow that lies opposite the featureless bulge on the other face.

Variations

Most sizable die breaks occur where the die neck meets the die face. This right-angle junction experiences elevated stress and is prone to chipping. Hobbyists refer to these corner die breaks as “cuds,” allegedly due to their resemblance to a bolus of partially digested bovine fodder. Shown below is a large cud on the reverse of a 1984 cent.

Die breaks with no direct connection to the coin’s rim are known as interior die breaks. Tiny examples, referred to as die chips, are common. Large interior die breaks are uncommon. Shown below is a 2007-P dime with a large interior die break that sits within a network of die cracks that indirectly connect the lump to the coin’s rim. Other dimes struck by this obverse die show that the cracks formed before the break. Large interior die breaks that show no connection to the rim are referred to as freestanding interior die breaks.

Anatomy of Die Breaks

Cuds can form spontaneously or may result from an impact. Shown below is a 1986 cent in which both dies experienced catastrophic impact damage. The impacts knocked off a large flake in the northwest quadrant of the obverse die.

Die breaks can appear fully formed, experiencing no further change in their shape. Other die breaks grow larger over time or form gradually as die cracks deepen and coalesce (as seen on the 2007-P dime). Shown below is a three-stage cud progression affecting a single 1982 obverse cent die.

The internal margins of cuds vary enormously, although most have a roughly convex shape. Crescentic cuds—like the Stage 3 1982 cent—have a concave internal margin. In rare cases, several crescentic cuds will meet up end-to-end to form a circumferential (360 degree) cud.

The base of a cud (the distance between the end points along the external margin) is usually longer than the vertex (the distance between the external margin and the most distant point along the internal margin). Elongate cuds present the opposite appearance. They have a narrow base and extend far into the body of the coin. Elongate cuds tend to form gradually as either a chain of interior die breaks coalesce, the edges of a wide die crack crumble away, or two die cracks meet up at some depth within the die face, creating a wedge of metal that breaks free. The ends of two elongate cuds can even meet up to form a rim-to-rim cud.

How Die Breaks Occur

One might reason that a corner die break forms in a manner analogous to how a stone tool is created. Stresses applied to the periphery of the die face should knock off a long vertical flake from the side of the die neck. The reality is just the opposite. Most die fragments that have been retrieved and that can be connected to known cuds arise from a horizontal fracture. They are quite thin, with the corresponding die void shallow.

Some die fragments fail to detach from the die face, typically sinking in instead of falling out. These are known as retained die breaks. They generate a low plateau on the coin carrying whatever portion of the design was on the working face of the die fragment. A rectangular retained cud appears to the left of the interior die break on the 2007-P dime shown above.

Die breaks are a fascinating window into the many forms of brittle failure that can affect a die.

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Mike Diamond has been collecting, researching, and writing about error coins since 1997.  He previously wrote a weekly column for Coin World (“Collectors’ Clearinghouse”) that focused on minting errors and die varieties.  Prior to that, he was responsible for dozens of articles that appeared in CONECA’s specialty journal Errorscope.  He created and contributed most of the content found in The Error-Variety Ready Reference.  Over the past 28 years, he has discovered or described well over 100 new error types.

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