Struck inside the collar beneath an overlying planchet, this Roosevelt dime became a uniface strike. Note the absence of a “wire rim” and the presence of faint ghost images on the obverse face of the undated coin.
In a normally functioning coinage press, planchets are fed into the striking chamber one at a time. But once in a while, two planchets are fed in together in such a way as to perfectly overlap each other.
The strike converts the two coins into a pair of complementary uniface strikes. The facing surfaces of the two coins end up with no design. Each error coin is designated a “full uniface strike” or a “full indent.”
The only kind of uniface strike that most collectors are familiar with — and the only one that grading services typically recognize — are those struck fully within the collar. These are usually termed “in-collar uniface strikes.”
The undated Roosevelt dime shown here is a typical example of a uniface error struck fully within the collar. The featureless obverse face is not flat like a pane of glass, but instead shows gentle undulations. The undulations are actually faint ghost images — an incuse suggestion of the reverse design and a raised suggestion of the obverse design. It should be noted that not all in-collar uniface strikes display recognizable ghost images.
In-collar uniface strikes derived from the bottom planchet are often confused with the early strikes of a uniface die cap. The illustrated Jefferson 5-cent coin depicts the latter error. A key difference is the presence of a gently sloping “wire rim” in the latter example. A uniface die cap starts out as a uniface strike but then sticks to the die and strikes additional planchets.
In-collar uniface strikes derived from the top planchet are rarer than those derived from the bottom planchet. The anvil die has to be recessed to an unusual degree to accommodate two planchets of normal thickness. The undated State quarter dollar shown here is a promising candidate, given that the obverse design is die-struck. However, some State quarter dollars were struck with the obverse die serving as the hammer die and others with it as the anvil die. There’s no way to be sure.
Uniface strikes that are also broadstruck (struck out-of-collar) are probably more common than in-collar uniface strikes, at least within the population derived from the bottom planchet. The undated broadstruck Lincoln cent depicted here is a representative example of this error type. The obverse face is featureless while the reverse face (not shown) is die-struck. Such errors are frequently — and mistakenly — encapsulated as “reverse die caps” by leading grading services.
The counterpart to this coin is, of course, a uniface strike with a die-struck obverse design. These usually curl up toward the hammer die when struck, creating a cap-like appearance. An example of such an error is shown here in the form of a 1991 Lincoln cent. Such coins are consistently and erroneously encapsulated as “obverse die caps.”
There’s no indication that this 1991 cent was struck more than once. A smooth transition exists between the featureless reverse face and the upturned wall. Had it struck another planchet (thereby becoming a uniface die cap) the transition zone would likely have shown a subtle disruption.
Internally, the coin features a single set of fine radial striations in the “slide zone” extending from the margin of the die-struck field to the edge of the coin. Had there been more than one strike, it is likely that the radial lines would have been interrupted by concentric strike lines.
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