By Jon Sullivan for PCGS ……
Although there are many valuable mint errors, among the loftiest of these are classified as “off-metal”. The most valuable mint error is a transitional off-metal 1943-D Lincoln Cent struck in copper, which was graded MS64BN by PCGS and sold for $1.7 million in 2010 to well-known collector Bob Simpson. The second-highest price for an error coin was another transitional off-metal error, this one being a 1943-S Lincoln Cent struck in copper in the grade of PCGS MS62BN, sold to Simpson for $1 million in 2012. Both of these coins are classified as transitional off-metals, which is a type of off-metal error.
So, what exactly is an off-metal error?
Defining Off-Metal Errors
When a coin is struck on a planchet that is different than its own, it is defined as an “off-metal”. This is because the planchet is different than normal either in its appearance, size, or both. A good example of this is the 1943 Lincoln Cent struck on a copper planchet (likely from 1942), instead of the normal zinc-coated steel planchet for that year. It also is the incorrect planchet for a 1943 cent, with a weight of 3.1 grams instead of the weight of a steel planchet – 2.7 grams. Both the metal and weight are off in that case, although the “denomination” of planchet it is struck on (a cent) is the same.
Off-metals most often occur when the planchet from one coin series is accidentally fed into the press of another coin series and struck. Common examples of this include quarters on nickel planchets, halves struck on quarter planchets, or nickels struck on cent planchets. In such examples, the planchet will be both the weight and metal content of a “normal” example for the respective planchet it is struck on. For example, if it is a nickel on a cent planchet, the coin will be the correct weight for a cent at 3.1 grams and contain the copper alloy for a cent.
There are a number of off-metal types, with some including transitional off-metals (struck in the correct series but on the prior year’s planchet that is of a different metal or weight); reverse transitionals (struck on the next year’s planchet, which is of a different metal or weight); struck on a foreign planchet (struck on the planchet for a foreign coin); or struck on an unknown planchet (this simply means the planchet cannot be identified).
Off-metals are known for most series of U.S. coins and with many world coins. Gold off-metals are particularly rare for both U.S. and world coins.
Also, some series of U.S. coins have no off-metals known at all for the run of years in which they were struck; for example, Liberty Seated Half Dimes are unknown as off-metals and Saint-Gaudens Double Eagles also have no known extant off-metals. Conversely, Lincoln Cents, Jefferson Nickels, and other modern coin series are fairly common as off-metals, most likely due to the massive production of the coins leading to a higher probability that mix-ups might occur within these massive coin mintages.
Valuing these errors can be either fairly easy or difficult, depending on the existence of similar pieces with marketplace data. Look around at auction sites and coin dealers’ websites to get a feel for values pertaining to a particular series and its off-metal type representatives. Values tend to be higher for rare dates of which few off-metals are known and less for the most common dates.
Typically, off-metals are collected within a particular coin series, such as Lincoln Cents (struck on dime planchet, foreign planchets, etc.), or simply as an error type, in which case collectors just collect any off-metal they can find in any series of coin. Error collectors have the luxury of collecting in whatever way suits their fancy, as errors are inherently unique.
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