Since mid-1982, cent planchets have been composed of zinc electroplated with copper. Errors associated with this process include plating that is absent, partial, blistered, cracked, peeling, excessively thick and abnormally thin. Cents struck on unplated zinc planchets are among the most sought-after plating mishaps, in part due to the dramatic color difference.
Unfortunately, unplated Lincoln cents are difficult to authenticate in even the best of circumstances, even for grading services.
Here, then, is a quick tutorial on how to identify genuine unplated cents. I will refer to three examples — a genuine unplated 1989-D Lincoln cent, a 1991-D cent chemically stripped of its copper plating, and a 1994-D cent that was plated-over with a silvery metal.
Seven diagnostics are key to evaluating a suspected unplated cent. Not all are definitive when considered in isolation, so one should consider the totality of the evidence. A genuine example will be characterized by some or all of the following features:
Diagnostic 1. Slightly underweight.
Unplated cents generally weigh between 2.42 grams and 2.48 grams. Our genuine 1989-D cent weighs 2.48 grams. The normal average is 2.50 grams.
Reduced weight is only a start, because a de-plated cent will also be underweight to the same degree. For example, our 1991-D cent weighs 2.47 grams.
As with any denomination, cent weights will vary, with some falling above or below the mean. It’s therefore possible to encounter a genuine unplated cent that matches or exceeds the weight of a normal cent.
Cents that have been plated-over are usually slightly overweight. However, our over-plated 1994-D cent weighs 2.5 grams — the same as a normal cent. I suspect that the host coin was originally underweight, with the added metal raising it to the standard value. While this was probably an accidental choice by the vandal, I wouldn’t put it past a crafty individual to weigh a large number of normal cents, set aside those that are slightly underweight, plate them with zinc, and still have a cent that’s slightly underweight.
Diagnostic 2. Smooth surface.