Papal States (1676) Piastra

Pope Innocent XI, whose papacy lasted from 1676 until his death in 1689, is notable for his power struggle with the king of France as well as his success in organizing Christian leaders in Central Europe to oppose the Ottomans. His numismatic legacy includes some beautiful coinage, including this (1676) Papal States piastra, which shows the pontiff on the obverse and Matthew the Apostle on the reverse. 

Genuine examples of this type generally sell for hundreds of dollars, with several examples in or near Mint State realizing well over $1,000 at auction in recent years. Numismatic Guaranty Company (NGC) recently received a purported example of this rare coin in a submission from a large auction house. 

The coin is missing a lot of detail, which is particularly noticeable in the head and feet of St. Matthew on the reverse. The coin also has rough, porous surfaces. NGC determined it is a base-metal cast counterfeit.

The denticles around the edge of the coin are incomplete in places and are marred by two prominent lumps at the base of the obverse. Additional lumps can be observed in some of the letters in the word MATTHAEUS. With cast counterfeits, a lump is typically caused by a small air bubble that becomes trapped when the mold is filled with molten metal. Many molds themselves also have defects and voids, which are then transferred to every counterfeit.

In addition to a visual examination of the coin, the “ring” test can be utilized; when a genuine coin is carefully balanced and gently tapped, it typically emits a clear, high-pitched ringing sound due to the uniform density and metallic composition of the struck coin. In contrast, a cast counterfeit—often made from lower-quality alloys or containing microscopic air bubbles from the casting process—will produce a dull, flat, or muted sound. While not foolproof, the ring test is a useful preliminary tool that, when combined with other authentication methods, can aid in detecting counterfeits.

Understanding the common flaws of cast counterfeits can help you identify fake coins like this one. If you still aren’t 100 percent sure that your coin is genuine, remember that NGC backs its determinations of authenticity and grade with the NGC Guarantee.

A version of this article appears in the July 2025 issue of The Numismatist (money.org).