PART IV. Die Errors:

Die Damage:

Intentional Die Abrasion:

Heavy Die Scratches

Definition: Die scratches are fine lines left in the die face by intentional or accidental die abrasion. Die scratches produced by intentional die abrasion usually travel in many different directions.

The images below show a 1983P Jefferson nickel with heavy die scratches. These scratches were left by the intentional abrasion of both the obverse and reverse dies to remove a strong die clash. Notice the varying length and random directionality of the numerous lines, which is typically seen when a die clash is removed.

PART II. Die Varieties:

Horizontal Mintmark (inevitably repunched)

Images are courtesy of Coppercoins.com

PART IV. Die Errors:

Die Clashes:

Horizontal Misaligned Die Clash (Conventional Type)

Definition:  A conventional horizontal misaligned die clash occurs when the hammer die is laterally shifted relative to the anvil die.  When the dies collide, the resulting clash marks are also shifted laterally.

This 1989 cent shows a bold horizontal misaligned die clash on the obverse.  The clash is less visible on the reverse.  When the clash occurred, the hammer (obverse) die was misaligned toward the right.  As a result the incuse Memorial is shifted toward the left on the coin itself.  The hammer die was slightly rotated as well when the clash occurred.

PART VI. Striking Errors:

Die Alignment Errors:

Horizontal Misalignment of the Hammer Die:

Definition: This occurs when the hammer die (typically the obverse die) shifts laterally to the anvil die. The die may shift within its recess when the bolts or clamp that anchors the die in place loosen up. The entire die assembly may also shift, carrying the die with it. A horizontal misalignment can be stable or dynamic. In a dynamic misalignment, the extent of a misalignment can grow or shrink. The direction of the misalignment can also change from one strike to the next. A loose die or die assembly can oscillate in opposite directions or spontaneously return to a centered position.

 If a horizontally misaligned hammer die collides with the anvil die, you end up with a horizontally misaligned die clash. If the misalignment was towards the south, the clash marks on the hammer die are positioned towards the north, relative to the southern arc of the design rim.

Part IV. Die Errors:

Hubbed-In Debris

Definition: When debris falls between the working hub and the considerably softer working die, the foreign matter is pressed into the latter.  When this foreign matter falls out, it leaves an incuse trace.  The foreign material will conform to the newly-formed recesses of the working die, as will its impression.  On the coin, the defect will appear as a raised imperfection that continues from the field to the design with no loss of clarity or relief.

This 1943 cent shows a thin ridge that extends from the design rim at 1:00 to a point near the base of Lincoln’s bust.  The ridge maintains a uniform thickness and relief until just before it fades out at its southern tip.  This ridge evidently represents the impression of a filament (metal or perhaps nylon) that was trapped between the working hub and the blank working die.  A few faint subsidiary ridges extend from the main ridge.  These may indicate that the filament was frayed.  Coin is courtesy of Robert Piazza.

Description: This is a machine used to automatically punch discs (or blanks) from a sheet of metal.

The image below shows a nickel strip that has had the blanks already punched out of it.

Image is courtesy of Heritage Auctions.

PART V. Planchet Errors:

Alloy Errors:

Gas Bubbles

Definition: On rare occasions a pocket of gas forms and expands when a planchet is struck. The heat generated by the strike is deemed responsible for the gas expansion.  The expanding gas pushes up the overlying metal, producing a rounded bulge with soft borders.  If the roof remains intact, the error is designated an “occluded gas bubble”.  If the roof explodes from the internal pressure, we call it a “ruptured gas bubble”.

If the roof is thin, it will flex or it will be left with a dimple when the tip of a toothpick is pressed into it.  If the roof is thick, it may not yield to pressure.

By definition, occluded gas bubbles are generally restricted to solid-alloy issues.  While gas bubbles are sometimes seen on clad coins, these always turn out to have been caused by heat applied externally outside the Mint.  Occluded gas bubbles should not be confused with blistered plating, the latter being an affliction restricted to copper-plated zinc cents.

A 1986-D cent with blistered plating is shown in the above images.  The blisters are unusually large.

The next set of images are of a 1958-D cent with a large occluded gas bubble above the date.

The last set of images show a 1949(P) cent with two occluded gas bubbles seen to the left of Lincoln’s bust.

Frosting – An effect seen on the raised parts of a coin whereby the metal appears to be crystallized. This is applied to the recessed areas of the working die.

Frosted devices – Raised elements on coins struck with treated dies to impart a crystallized appearance.

The below image shows frosting applied to Liberty, the word LIBERTY, the date and the motto on a half ounce platinum bullion coin. Image courtesy of Heritage Auctions.

Part VI. Striking Errors:

Uniface Strike:

Full Uniface Strike

Definition: Occurs when a planchet is perfectly centered over another planchet or coin and the two are struck together.  This error is also known as a full indent.

When an off-center planchet or coin is struck against an underlying planchet, this is known as an off-center uniface strike.

A full uniface strike can affect the face struck by the hammer die or the anvil die.  The coin can be struck in-collar or out-of-collar.

Above are photographs of a state quarter with an in-collar uniface strike.  Since state quarters were struck with conventional and inverted die setups, there’s no way to determine whether the die-struck obverse design was struck by the hammer die or the anvil die.

The coin depicted above is a cupped, uniface broadstrike.  It is what the companion of the previous coin would have looked like.  When two planchets are placed on top of each other and struck out-of-collar, the top coin curls up toward the hammer die, which in this case was the obverse die.  Because of its steeply upturned wall, coins like this are often mistaken for die caps.  But there is no convincing evidence that this coin was struck more than once.