Error Coin Essentials: Die Caps

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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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Die caps are enduringly popular among error collectors. They originate in a straightforward fashion, developing when a coin sticks to a die and proceeds to strike one or more incoming planchets. They are primarily defined by the process inferred from physical evidence, but grading services, dealers, and collectors frequently ignore the definition and misinterpret physical evidence, leading to rampant misuse of the term “die cap.”

Hammer & Anvil Die Caps

Shown above is a 1999 cent in the form of an obverse (hammer) die cap. It’s best to specify whether a particular example is a hammer or anvil die cap, as the obverse die can function in both capacities depending on the time period. In this example, a newly struck cent attached itself to the retreating hammer die and struck the next planchet. With both coins unconstrained by the collar, the perimeter of the top coin curled upward around the neck of the hammer die. More importantly from a diagnostic standpoint, the reverse design was flattened and expanded, providing the necessary proof that a planchet had been struck.

Next up is a 1999 cent in the form of a reverse (anvil) die cap. Here, a newly struck cent remained on the anvil die after the strike, and a fresh planchet was fed in on top of it. The two discs were struck together out-of-collar, resulting in massive expansion. The obverse design of the bottom coin is grossly enlarged and distorted, once again affirming that this is a die cap.

Misidentified Die Caps

Our third 1999 cent might look like a die cap, but it isn’t. The planchet represented by this coin was struck once on top of a newly struck cent, leaving its underside with a brockage (an incuse mirror-image version of the design). Any disc will cup toward the hammer die when struck on top of a second disc, especially when both are struck out-of-collar. This coin is the counterpart of our anvil die cap, with the two forming a “cup-and-saucer” mated pair. Individually, such an error should be referred to as a cupped broadstrike with a full, centered, first-strike brockage of the obverse design on its reverse.

All grading services have a 100-percent failure rate in properly diagnosing such errors, preferring to call them as die caps. I presume they are misled by the cupping. In isolation, cupping is only a reliable die cap diagnostic when the “wall” is unusually high.

Die Caps Versus Other Errors

An abundance of evidence indicates that most cupped, brockaged coins are produced in a single strike.

1. Each cup-and-saucer mated pair involving a double-struck anvil die cap also incorporates a cupped coin with a brockage on its underside.
2. The brockage on our cupped cent is clear and complete. Since zinc is a soft metal, a strike against a second planchet would effectively obliterate the center of the brockage.
3. A strike against a fresh planchet would leave the latter with a counterbrockage (an expanded, raised, correctly facing obverse design that’s cut off along the coin’s edge). I’ve seen less than a dozen counterbrockages on zinc cents. In contrast, I’ve seen hundreds of cupped, brockaged cents. Counterbrockages would outnumber cupped brockaged cents if the latter were die caps.
4. If a vertical wall were an indicator of two or more strikes, then you’d expect a greater number struck only once. These would presumably have a lower wall with less acute cupping. And the brockage would be even clearer and less expanded. For all intents and purposes, such coins do not exist.
5. Grading services also misdiagnose cupped coins with featureless undersides as die caps. Most are the product of a single strike and are properly referred to as uniface broadstrikes. They form when two planchets are struck together out of collar. The top coin cups toward the hammer die while the bottom coin (also uniface) generally expands in the horizontal plane.

Taking a clue (unfortunately) from our anvil die cap, grading services also tend to identify any coin that’s grossly expanded in the horizontal plane as a die cap. Many of these are also the product of a single strike or, if struck more than once, fail the defining requirement of a die cap by never having been struck against another planchet.

Conclusion

I could fill many pages on the subject of what is and isn’t a die cap, but I’ll end by saying that most coins that are labeled as die caps are something else.

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Mike Diamond has been collecting, researching, and writing about error coins since 1997.  Since November 2009, he has written a weekly column for Coin World (“Collectors’ Clearinghouse”) that focuses 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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