Part IV. Die Errors:

Die Damage:

Collar damage

Definition: Mechanical damage affecting the working face of the collar. This damage can appear as scratches and grooves that are horizontally or vertically oriented.

This 1970-D nickel features a sizeable cud (corner die break) on the obverse. The section of the edge next to the cud carries coarse vertical grooves that reflect damage to the collar. It’s possible that gritty debris derived from the collar break became trapped between the neck of the anvil die and the collar. Either that, or a collision with a foreign object that was responsible for the cud also caused that foreign object to shatter, with the resulting debris getting trapped between the die neck and the collar. Vertical movements of the anvil die relative to the collar ground the debris against the collar, generating the vertical grooves. Every nickel struck afterward carries the impression of that damage. The grooves on the nickel could be partly an impression of the damage and partly due to the nickel scraping against the damaged portion of the collar during ejection.

The upper member of these two 2008-P New Mexico quarter dollars displays unusually wide, flat valleys between the reeds, with the valleys carrying heavy horizontal scratches. This appearance reflects the fact that the ridges on the working face of the collar were abraded and truncated. Similar damage is known from other dates, including 2007-P Wyoming quarters. This damage may have been produced when the beveled entrance of the collar was being machined or de-burred. The rotating machine tool may have slipped into the functional portion of the collar, damaging the reeding.

Part V. Planchet Errors:

Plating Errors:

Cracked and Peeling Plating

Definition: Plating that cracks or peels up before or after the strike. Among copper-plated zinc cents, this type of plating error is comparatively rare.

This 1984 cent shows extensive cracking of its copper plating. Some has peeled up or is in the process of peeling up toward the southeast periphery.

Struck sometime in the 1980s, this off-center cent was struck on a partly-plated planchet. What plating is present is peeling up in many areas. The peeling can be seen on both the unstruck and struck portions of the coin.

Part VI. Striking Errors:

Intra-Strike Damage:

External Struck-Through Errors (With Cupping)

Cross-referenced as:

Part VI. Striking Errors:

Cupping:

On Unobstructed Strikes:

Forced:

By Foreign Object or Machine Part

Definition: The unstruck portion of an off-center planchet is forced down upon an underlying obstruction by the impact of the hammer die. This forces the unstruck portion of the coin upward and simultaneously leaves the underside of the unstruck crescent with an indentation which is called an external struck-through error.

This 2000-D Virginia quarter was struck off-center. The portion of the planchet that protruded outside the striking chamber rested on an obstruction. The impact of the hammer (reverse) die caused the presumed foreign object or machine part to push the unstruck crescent into a vertical orientation. It also generated a short arc of design rim. The external struck through error can be seen on the outside of the cupped portion of the unstruck crescent.

This off-center 2003 India 5 rupee coin features an external struck-through error and forced cupping generating by the foreign object or machine part that was positioned beneath the unstruck portion of the coin. The unstruck crescent is tilted upward at an angle of around 45 degrees. An arc of design rim formed along the base of the internal surface of the inclined metal.

Part IV. Die Errors:

Die Breaks:

Retained Cuds:

Outthrust Die Fragments

Definition: A coin struck by a retained cud (retained corner die break) in which the die fragment protrudes beyond the plane of the die face.

In most retained cuds, the die fragment sinks in, beneath the plane of the die face. This leaves this part of the coin’s design sitting on a low plateau. In rare instances, the die fragment protrudes beyond the die face, generating an island of design on the coin that is recessed. In order for the die fragment to protrude, it’s possible that bits of die steel or other debris become wedged in between the die fragment and the intact portion of the die neck.

This 1965 quarter dollar takes the form of an enormous broadstrike. The northeast quadrant of the reverse face was struck by an outthrust die fragment (outthrust retained cud). The grossly smeared letters of AMERICA are recessed relative to the rest of the design. This area is demarcated internally by a relatively thick ridge that represents coin metal that extruded between the die fragment and the intact portion of the die face. This means that the die fragment was also displaced laterally (lateral spread).

Part VI. Striking Errors:

Sandwich Strike:

Definition: A planchet or coin that is struck between two other discs. Coverage can be complete or partial on one or both faces.

This off-center planchet was struck between two other planchets. The planchet that overlapped the obverse face generated an internal indent, while the planchet that overlapped the reverse face produced a uniface strike.

This enormously expanded coin represents a planchet that was situated between two previously-struck coins during the strike. One coin generated a full, centered, first-strike brockage of the reverse design on the obverse face. The other coin was a considerably off-center cent that generated a 90% partial brockage of the obverse design on the reverse face. Incuse design elements on this face are limited to the back of Lincoln’s head and the motto LIBERTY. The rest of the surface is featureless, since this is the impression of the unstruck portion of the coin.

Part VI. Striking Errors:

Brockages:

Brockage From Struck Die Fill

Definition: A brockage generated by a previously-struck accumulation of compacted die fill or “grease”.  This doesn’t happen very often because the die fill has to have just the right consistency.  It can’t be so soft or so hard that it doesn’t strike up, and it can’t be so soft that it is unable to transfer its design to a planchet.  Beyond that, it has to rise high enough above the die face to stand a chance of contacting the opposite die when a planchet fails to be fed into the striking chamber.  This would probably need to coincide with an unusually small minimum die clearance.

Alternatively, the layer of die fill needs separate from the die it was attached to, and either fall onto or stick to the opposite die so that the side that had molded itself to the die face is oriented toward the planchet.

A brockage from struck die fill would be expected to show some of the following characteristics:

1. Indistinct borders
2. Uneven outline
3. A coarse texture affecting both the brockage and the surrounding recess
4. Indistinct incuse details
5. Additional, entirely separate areas that have been struck through “grease”

This undated 5 rupee coin (1992-2004) displays a brockage of the Ashoka lion on the reverse face, which was struck by the hammer die.  The brockage is perfectly aligned with the die-struck lion on the obverse face.  This brockage satisfies the first four conditions listed above.  Additionally, the smeared Hindi script beneath the lion suggests an unusual composition.

Another possible source for a brockage with these characteristics is a struck floating encrustation.  These are flakes of compacted detritus that emerge from the guts of the press.

Part IV. Die Errors:

Clashed Dies:

Mule Clash

Definition: Clash marks from dies that should never have been paired.  Mule clashes were, until recently, considered a 19th century phenomenon.  Six are known from this century:

1. An 1857 Flying Eagle cent that shows a clash between its obverse die and the obverse die of a $20 double eagle gold coin.
2. An 1857 Flying Eagle cent that shows a clash between its reverse die and the reverse die of a Seated Liberty quarter dollar.
3.  An 1857 Flying Eagle cent that shows a clash between its obverse die and the obverse die of a Seated Liberty half dollar.
4.  An 1857 Seated Liberty quarter dollar that shows a clash between its reverse die and the reverse die of an 1857 Flying Eagle cent.
5. An 1864 2 cent coin that shows a clash between its reverse die and the obverse die of an Indian Head cent.
6. An 1870 Shield nickel that shows a clash between its obverse die and the obverse die of an Indian Head cent.

It’s widely suspected that all of these mule clashes are the result of mischief by mint employees.

The latest mule clash was discovered in 2018 by Amy Antone in a pile of cents diverted from pocket change.  It appears on the reverse face of a 1999 cent.  Appearing on the left side, just inside the design rim, is an arc of incuse, mirror-image letters (“oF AMERIC”).  The letters are doubled, documenting two die clashes that were slightly offset from each other.  The tops of the letters are slightly cut off, indicating that the die responsible for the clash was slightly misaligned toward the left.  The peripheral location of the letters indicates that one of the two dies (presumably the hammer die), was tilted.

It’s not clear whether the two dies were actually installed in a press at the time of the clash.  It’s also unclear whether this clash was accidental or intentional.  This bizarre clash comes from an 11-year time period (1990-2000) that produced over 34 “radical MAD clashes” in Lincoln cents.  All of these clashes are weak, tilted, and often drastically misaligned.  The conditions that led to these clashes may have contributed to the production of this mule clash.

Part IV. Die Errors:

Die Deterioration/Deformation Errors:

Severe Die Wear:

Design-Devouring Die Wear

Definition: Die wear that results in the lowering, thinning, and disappearance of design elements.  Conventional die wear usually results in the expansion of letters and numbers, which is often accompanied by indistinct and irregular margins.  In design-devouring die wear, letters and numbers become lower, thinner, and smaller, while retaining their shape.  This pattern of design distortion is caused by a retreat of the field portion of the die down to the deepest levels of the die’s recesses.  Letters and numbers are narrowest at the bottom of their respective recesses.

The obverse face of this 2012-P Denali National Part quarter dollar shows design-devouring die wear.  The motto IN GOD WE TRUST is most severely affected.  Design-devouring die wear is common in the AMERICA THE BEAUTIFUL series of quarter dollars.

The lower half of this 2015-P dime shows the effects of design-devouring die wear.  The letters of IN GOD WE TRUST are quite thin, while the date and mintmark have nearly disappeared.

The periphery of this 1988 cent shows development of a “ridge ring”, a form of die wear common in zinc cents.  Here the field portion of the die has retreated, and this has resulted in thinning of the motto IN GOD WE TRUST.

Part IV. Die Errors:

Die Deterioration/Deformation Errors:

Design Berms

Definition: A raised line or shelf that partly or completely encircles a design element.  The berm is usually associated with large central design elements, like busts and buildings.  Peripheral elements, like letters and numbers, are rarely affected. Unlike conventional forms of die deterioration doubling, the berm is clearly demarcated from the normal design.  Berms appear to develop quickly and prematurely, as there are seldom any other signs of die deterioration, such as flow lines and orange peel textures.

A sharply defined berm completely surrounds the bust of Elizabeth II in this 2017 British 1 pound coin.  Apart from a few “starburst” streaks at 1:00, there are no other signs of die deterioration.

The bull on the reverse face of this 1996 Irish 5 pence coin is partly surrounded by a berm.   The berm is best developed on the bull’s back and around its hindquarters.  Both faces of this coin also feature a raised ring just inside the design rim.  The ring is more strongly developed on the reverse.  These rings represent another, perhaps unrelated, die deformation error. Photos by Jeff Ylitalo.

In this 1962 Canadian cent, a patchily developed design berm extends out from the bust of Elizabeth II in the form of a low shelf.  The berm appears along the front and back of her neck, her mouth, and her hair ribbon.

Part XI. Non Errors:

First strike authentic;

Later strikes counterfeit

This 1985 cent shows a second strike that was delivered by a pair of counterfeit dies.  The counterfeit strike is vertically-oriented in the photos and appears on the left side of each face.  One of the counterfeit dies was tilted (vertically misaligned), which is why the strike is restricted to one half of the coin.  I have seen two similar specimens, both originating in Canada.