Tuesday, September 26, 2017

XRF testing

At the ANS seminar Counterfeits: the Threat to Collecting and Scholarship several people from the museum community remarked analyzing the metal in coins using X-ray fluorescence (XRF). This technique is said by some people to be nearly as good as other techniques that are much more expensive.

If a coin contains modern elements, or if a coin has a different composition than a large group of known genuine coins, then it is likely false.

I asked who can provide such a service to private collectors — but no one had recommendations.

I received an unsolicited email recently from Phil Keck at Artemis Testing Lab. They offer XRF on ancient materials for $200. Two samples per item.

An eBay search found a service in Flushing Queens that will test coins (or anything else) for $20 a sample. The auction picture shows a Niton XL2 gun. Such guns can be purchased for $15-20k. I believe they can be rented as well. I am not sure how common such services are. A friend told me several years ago of one in a coin shop in Louisville KY.

If anyone has submitted ancient coins for XRF testing I would be curious to see what kind of reports you received and if they were helpful. If anyone is near New York and wants to try the service in Flushing or knows of a similar one perhaps a field trip could be organized to test coins. Any takers?

Saturday, September 16, 2017

Black Sea Hoard dies

The American Numismatic Society hosted a seminar on Counterfeits: the Threat to Collecting and Scholarship with presentations by David Hendin, Robert Hoge, and Ute Wartenberg.

For me the most exciting part was inspecting dies from the group of counterfeits known as the “Black Sea Hoard.” In his book Counterfeit Studios and Their Coins Ilya Prokopov describes this hoard as the work of “Studio ‘Varna-1’”. The dies are said to be the work of a single master engraver. Coins produced by these dies were sold openly in museums as replicas. They were also being sold as genuine to collectors.

These dies represent the mints of Apollonia Pontika, Mesembria, Istros, and Chersonesos. The Chersonesos dies troubled me because they were unfamiliar. I recognize the style of the Varna-1 engraver's work on facing head coins. The Chersonesos dies are by the same sculptor. My inability to recognize them proves my understanding of that style of the artist's facing head fakes is overconfidence. I am not sure I would recognize fake Chersonesos coins without carefully consulting a scarce pamphlet-book Modern Forgeries of Greek and Roman Coins by Dimitrov, Prokopov, and Kolev.