We’ve all heard of instances of ‘contemporary forgery’ – fake money produced cheaply to imitate and circulate alongside legitimate coins or notes. ‘Modern forgery’, on the other hand, refers to the process of producing a copy of a coin from an earlier period.

Some of these modern forgeries are poorly produced in low-value materials and large numbers, and are targeted at the tourist market, where the audience might be more easily deceived. However, others are of higher quality, aiming to achieve high valuation sales to dedicated collectors. The higher profit margins in this kind of modern forgery mean that it is worthwhile putting in effort and investment for higher returns.

Laura Perucchetti, a scientific researcher at the British Museum, discusses a specific case of modern forgery within the museum’s collections. She describes why the artefacts attracted suspicion, how they were tested, the theories on how these convincing forgeries may have been created, and what can be learnt from forgeries of this kind.

In 2017, a researcher visited the British Museum to compare a bronze coin on sale to those held in the museum’s archives. Closely examining these artefacts, Amelia Dowler, the former curator of Hellenistic coins at the British Museum, became suspicious of three coins in the collection thought to originate from the island of Ithaca and date back to the 3rd-2nd centuries BCE. Their stylistic differences and unusually uniform appearance raised questions about their authenticity.

The coins feature the head of Odysseus on the obverse and a standing cock on the reverse. They could be divided into two groups based on their design variations. Variant 1 coins had a full inscription and monogram on the reverse, while Variant 2 coins had a shorter inscription and lacked the monogram.

X-ray fluorescence analysis conducted by Perucchetti revealed that the two groups also differed significantly in their chemical composition. Variant 1 coins were found to be typical bronze alloys of the Hellenistic period, containing 8-11% tin and 1.1-2.7% lead. These compositions were consistent with the purported age of the coins. In contrast, Variant 2 coins were brass, containing 13-16% zinc, along with varying amounts of tin, lead, arsenic, iron, silver, antimony, and nickel.

The presence of zinc in Variant 2 coins raised serious doubts about their authenticity. Examples of copper–zinc alloys dated to the 2nd century BCE or even before are not unheard of. However, they are rare. Coins made from this combination were not common in the Hellenistic period, with the earliest known examples appearing in Phrygia and Bithynia during the 1st century BCE. These authentic early brass coins were clearly differentiated from other copper-based coins and were made with refined copper, unlike the Variant 2 coins, which contained lead and tin.

Furthermore, the Variant 2 coins were found to be produced as a distinct series of coins, rather than being just another type of coin that happened to contain zinc. This implies that the presence of zinc in the Variant 2 coins was not accidental. This contrasts with the first Hellenistic copper-zinc coins, which were likely created specifically as a substitute for silver coins during a shortage of silver.

So, where did these Variant 2 coins come from?

Dowler’s investigation revealed that the earliest known example of these coins was part of the Prokesch Osten Collection. Anton von Prokesch Osten, an Austrian diplomat who assembled a large and significant coin collection, recorded the shortened inscription of the Variant 2 coins in his manuscript catalogue circa 1873-1875. This suggests that the Variant 2 coins were likely modern forgeries produced before this period.

Perucchetti compared the composition of the Variant 2 coins to 19th-century European copper-based objects. However, the coins were different as they had a slightly different composition, in particular an unusually high silver content. This led Perucchetti to speculate that the forger used ancient metal to create the forgeries, aware that the contemporary refined copper would be easily detectable.

It is plausible that the forger, possibly a skilled metalsmith and antiquarian, was aware of the emerging studies documenting the chemical composition of ancient metal artifacts. They may have known that the refined copper of the 19th century would produce a different composition compared with ancient coins and be spotted as a fake. To create more convincing forgeries, the forger likely remelted small, ancient objects and coins to produce the metal for the forgeries. Because of the zinc content, these would probably be from the Roman Imperial Age or later.

Unfortunately, very little is known about modern forgeries of ancient copper coins. But we do know a little more about techniques used by forgers of silver and gold coins. The most famous case of the modern era is probably Karl Wilhelm Becker, a German forger who operated at the end of the 18th to the beginning of the 19th century. He would use less valuable ancient coins and stamp more valuable designs onto them. He would also imitate wear and tear by burying the forgeries in manure and mixing them with pieces of iron.

The Ithaca coins studied by Perucchetti may be one of the first examples of this type of clever and informed forgery that used scientific knowledge to create more plausible fakes. This occurs today – specialists use increasingly sophisticated techniques to detect fakes, while forgers use their findings to create increasingly credible counterfeits. Perucchetti’s findings suggest that this cat and mouse game has been playing out for a long time.

This study highlights the need for continued research and vigilance in the field of cultural heritage protection. As experts develop increasingly sophisticated techniques to detect fakes, forgers will likely continue to adapt their methods. It is crucial that researchers remain committed to unravelling the secrets of the past while safeguarding our cultural heritage from deception and fraud.

By understanding the techniques and motivations of forgers throughout history, researchers can develop more effective strategies for identifying and combating modern forgeries. The Ithaca coins serve as a reminder that the authenticity of even the most convincing artifacts must be carefully scrutinized, and that the pursuit of knowledge in the field of archaeology must always be tempered with a healthy dose of scepticism.