Ancients Today column from the Sep. 5, 2016, issue of Coin World Monthly:
The Julio-Claudian emperors struck large quantities of copper, bronze and brass coins, which circulated throughout the empire and even reached beyond Rome’s borders.
In general, the Romans were able to distribute these coins in adequate numbers, no matter how distant the province.
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Even so, occasional coin shortages occurred in Rome’s Western provinces, which incorporated areas of modern-day Spain, Portugal, France, Britain, Germany and the three nations of the Benelux Union (Belgium, the Netherlands and Luxembourg).
These shortages were caused by many factors, including economic problems, regime changes, political instability, and unanticipated difficulties in delivery. During those times old and worn Roman coins were liable to be countermarked by Roman officials to extend their use.
Alternatively, unofficial mints operated as private ventures would issue coins to fill in the gaps. This phenomenon was especially interesting in the Western provinces during the age of the Julio-Claudians (27 B.C. to A.D. 68). We must presume that the main goal of these forgers was to earn a profit from their minting (or casting) efforts.
Making money by faking money
Profits could be generated by forgers in a number of ways. Frequently a coin of precious metal would be imitated with a plated coin. The maker hoped the plated pieces would pass undetected into commerce at the full value of an official silver coin.
The imitative plated denarius of the Emperor Claudius (A.D. 41 to 54) shown is a perfect example. This type is found in Britain and there is no reason to doubt it was struck on the island.
The details of the designs and inscriptions are closely modeled after official Rome-mint denarii, yet the style and fabric are divergent enough to mark it as an unofficial issue (even if it hadn’t been merely silver plated).