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?

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.

The difficulty of photographing gold coins

Here are six professional pictures of the same coin.

These pictures appeared on the auction catalog or web sites of numismatic auctioneers Harlan J Berk, Classical Numismatic Group (twice), Heritage, Stack's Bowers, and the coin grading company Numismatic Guaranty Corporation.

These images were taken over the span of eighteen years. The version with the red background was scanned from a printed auction catalog. All of the other images are taken directly from auction sites or the slab company's slab verification image.

This coin did not change color in the last 18 years. Something about the lighting situation and the camera's color profile was different enough that each of these pictures is different.

What color is the coin really? In my memory the coin looks like the middle coin on the left-hand side. Yet when I held the coin over my computer monitor in a room lit by compact florescent lights it looked most like the upper right image.

Can the output of my computer be trusted? In the days of CRT monitors the color balance could be tuned and there were reference images for that purpose. LCD monitors are not as color-accurate as tuned CRT monitors. Perhaps I should repeat the experiment in the sunlight? Bottom-line: I am not certain which image is the most accurate.

Database of Digits Extracted from (modern) Coins

Xingyu Pan and imageLaure Tougne have published a paper describing their database of digits extracted from scans of modern coins.

The database of 3000+ images itself cannot be directly downloaded. They explain here that you may request it from them.

The paper is good! The databases discussed are

• 606 digit images manually cropped from high-resolution photographs of well-conserved coins
• 1,200 digit images automatically extracted from a subset of a PCGS database containing coins in different states of preservation
• 1,200 digit images manually extracted from the same coin photographs as above

Although the new dataset only contains digits from modern coins the authors discuss the literature of recognition of ancient coin lettering. There are as yet no public databases of images of the digit or letters extracted from images of ancient coins.

Antiquities Memorandum of Understanding with Libya

Please read Cultural Property Observer and comment on the Libyan MOU. If the MOU is completed and includes coins it will become difficult for Americans to buy ancient coins from Kyrene in European auctions. It will also be difficult to import Ottoman coins from the territory of modern Libya.

Do it this weekend or it will be too late.

Recognizing Roman coins with neural networks

Jongpil Kim of Rutgers university reports a neural network capable of correctly recognizing the emperor 73% of the time from coin images. The reverse type is recognized 67% of the time.

The report is available on SEQAM and the paper is available by clicking PDF on this Cornell library site.

Ancient Astronauts

Mike Markowitz covers The “Alien” Coin for CoinWeek.

Video on creating 'coins' with CNC machine

I stumbled across this 9 minute video which shows the process of creating a medallion with realistic bust using a CNC machine.

The medallion produced looks quite good! It looks better than most of the 'coins' featured in do-it-yourself coin making videos. Yet most of the steps made me cringe because I was certain he was doing it the wrong way.

Once he has a 3D model on the computer, he feeds a block of metal to a CNC machine rated only for wood. I was sure something would go wrong but he got it perfect.

To produce the round shape he just takes his metal block and starts hitting it with a belt sander! I was certain he was doomed but it looked very nice when complete.

To give the appearance of patina he uses spray paint. I was amazed that this worked at all! He got a nice effect in the end.

The final medallion suffered a bit of a 'staircase effect' on the face due to the limited depth control. I would have liked to see if he could have removed that with a bit of polishing. Even with the depth artifacts he managed to produce a pretty nice medallion using techniques I would not have expected to be effective.

Print on demand catalog of the coins of Troas

I recently purchased a Print on Demand copy of Warwick Wroths 1894 catalog of the British Museum collection Catalogue of the Greek Coins of Troas, Aeolis, and Lesbos.

Google scanned three copies of this book: from the University of Michigan, from the New York Public Library, and from Harvard

The Harvard copy doesn’t seem to show up in an ordinary Google Book search. I found it using this link: http://fig.lib.harvard.edu/fig/?bib=002349380.

Public domain books that have been scanned by Google can be printed on demand. To order online, just bring up the book in Google Books, click “Get this book in print” and “On Demand Books” and several vendors appear. I wanted to see an Espresso Book Machine in action. There is one at the McNally Jackson bookstore in Manhattan. So I went down there, armed with the title.

The machines aren’t self serve. I gave the operator my title, and he brought up the University of Michigan Copy. I had hoped to see it printed but the machine apparently takes a while to download the book. It downloaded overnight and the operator printed it the next morning. I was surprised to find I had received Harvard’s copy.

The problem with getting a different copy than expected is that Google’s 2008-9 analysis did a poor job of distinguishing photo plates from line art. For numismatic books this is a problem. If the Google book preview shows a coin “posterized” the print on demand copies print it as a black blob. Luckily Harvard's copy is better than the U of M's.

Here are three copies of plate 8. On Harvard and the NYPL’s copy, coins #1, #2, #18, #19 and the reverse of #22 are shown greyscale. On the U of M’s copy, none of the coins are shown greyscale. They all appear as “posterized” four color art.

The “posterized” coins appear as black blobs when the Book Machine prints them. I am not certain this is the fault of the book machine. It is unfortunate that there is no way to supply feedback to Google books that a page or part of a page is greyscale artwork.

There is also no way to specify that the printed size of the page is meaningful. This is not a huge problem for the BMC volumes, which originally appeared the similar in size to what the Espresso Book Machine prints.

I paid $17 plus tax for this volume. For comparison, the hardcover decent plate Italian edition by Forni from the 1960s can be found used for $50, with other copies selling for more. The original version can sometimes be found at auction for $150+.

Many years ago I wanted to get folks with original BMC volumes to scan the plates. I had hoped to assemble a plates-only PDF. I managed to scan a few volumes myself but was not able to get the needed volumes and the project fell through. Perhaps with the British Museum putting their collection online the need for this has passed?

Artist Mike Bouchet makes art gallery smell like money

(via BoingBoing!): Perfume maker perfects the smell of American paper currency.

ISEGRIM search form

ISEGRIM is a database of 60,000 Greek coins of Asia Minor developed by Otfried v. Vacano at the University in Düsseldorf. There are no pictures. Unlike other search sites, instead of filling out forms the user was to write "queries" using a special syntax similar to Lucene. Although powerful, it has been difficult for computer novices to use.

I created a proof-of-concept for searching ISEGRIM using forms. My experimental site is at http://isegrim.mybluemix.net. If you already know ISEGRIM this site still gives one advantage because it alters search responses to the BMC Greek catalogs to be hyperlinks. So if you are in the United States you can just click to go to the BMC description (then search for the plate, if any).

I sent an email to the ISEGRIM contact address but got no response. It is possible they will ask me to take it down. Or maybe they will let me contribute it to their site.

This is a proof of concept. Let me know if it helps.

Odd surface on presumably fake coin

I show here two coins from the same die pair. The high grade example is a Bulgarian replica of a Neapolis stater. The damaged example was sold as genuine on eBay this spring.

This replica shows up being offered from time to time as genuine. This new example surprised me because the damage is so strange. Here is a close-up:

Several things are going on. Pieces are broken off! There is strange cracking that follows the shape of the gorgoneion. There is a lot of wear both normal and strange looking.

Has anyone else seen a coin with this coin of surface?

3D model of Kushan coin

The Institute of Archaeology of the University of Warsaw has provided a remarkable 3d scan of a Kushan bronze coin. The model was done by Otto Bagi and Sergi Mañas Jolis. Apparently photogrammetry was used to to infer the 3D coordinates.

I am inquiring what kind of equipment and software is needed to produce such models.

The team also has a nice model of an Alexander tetradrachm and a cupped Byzantine coin. All the models can be rotated and zoomed with your mouse or trackpad.

Is this 'panther' Cerberus?

Numismatic Naumann, auction 46, lot 182

Medusa is not the only creature in Greek mythology with snakes for hair. The monstrous dog Cerberus, who fought Herakles, had a mane of snakes.

Coin depictions of Cerberus (electrum hekte, Italian bronze, Roman aureus) show the monster with two or three heads but no snakes. Vases often show snakes.

There is an animal with snakes in its mane on a very rare Greek coin. This diobol (weight 1.08g, 11mm diameter) seems to depict an animal with a mane of snakes on the reverse. The animal has whiskers and triangular ears. The coin is rare; I have only been able to locate two other examples.

CNG e-334, lot 157

CNG 73, lot 419, no snakes

I suspect that this coin reverse depicts the head of Cerberus. In addition to the snakes, the ears resemble the ears of Cerberus on vase paintings. Some dogs have whiskers, and some Greek and Roman art shows Cerberus with a at least one lion head. Thus, none of the features rules out Cerebus. In addition, Cerberus is not always depicted with multiple heads.

The reverse is thus not a generic panther or lion as suggested by the catalogers of the coin example, but a rare depiction of Cerebus with a mane of snakes.

Identifying a bronze coin using Münsterberg

I purchased this coin in 2004 from Clark's Ancients. It had been identified as being from Abdera, like the first example on this CoinTalk thread. It did not look like that type. It had previously sold in 1980, and the tickets that came with it showed several unsuccessful attempts to ID the inscription.

I didn't even think the animal looked like a griffin. It looked more like a panther. I did some basic searching on sites such as Wildwinds, The ANS' DONUM, ISEGRIM, and dealer sites but found nothing.

There is an inscription, perhaps ΑΝΔΡΟΝΙΚ. Both the dealer and the collector, Biblical coinage expert James Lovette, had tried to identify the coin and failed. I spent a long time on it and got nowhere. I took another look at it this week and identified it in under an hour. The inscription ΑΝΔΡΟΝΙ? previously recognized by myself and the other experts appears in Münsterberg's 1911 book listing the names of Greek coins. I scanned the book with help from Pat Lawrence and put it on my web site 10 years ago!

The entry is here. (Interestingly, that link takes me directly to the entry in Chrome but in Safari 10.0.1 only to the top of the page.)

Münsterberg names ten cities: Ambracia, Adramyteum, Cyme, Teos, Rhodus, Saittae, Apamea Phr., Trapezopolis, Sala, and Laodicea, naming the magistrate Ἀνδρόνικος (Andronicus).

Back in 1911 the reader would have followed each entry to Münsterberg's entry for the city, which would cite the work the entry is to be found in. Today it is much easier just to go to popular ancient coin search engines, like Wildwinds. I searched all those cities again, and nothing resembling my coin showed up.

At this point I SHOULD have fallen back on using the book as Münsterberg had intended. I had failed at that before. I went to my next identification technique: flipping through all the volumes of SNG Copenhagen looking for a match. I found a similar coin in the Epirus volume, for Ambracia, naming a different magistrate. This match gave me the strength to search Ambracia again, and a Google Image search for 'Ambrakia Griffin' turned up this sales record.

Where did I go wrong with Münsterberg? His first reference is to 'Rollin n. 3160'. This is where I had gotten stuck in 2004. Since that time HathiTrust Digital Library has scanned and placed online the 1864 catalog by coin dealers Rollin and Feuardent. The entry for #3160 gives the reverse as 'Griffon marchant à dr.; dessous, ΑΝΔΡΟΝΙΚ' and gives a price of three francs. So a match was found.

Because the type is rare and low-value no examples with photos exist on ancient coin database sites. The example found on the dealer aggregator VCoins was found through a Google search. (VCoins itself doesn't allow sold coins to be searched for.) The ANS and British Museum both had examples in their databases, but neither had photos or inscriptions recorded, so I didn't find them. I was unable to find any examples naming the magistrate Andronicus.

The coin itself is very thick. I am surprised it was assigned 238-168 BC by Percy Gardner in his 1883 catalog. I suspect much earlier. I was wrong about the panther — on better examples the wings of a griffin can be seen.

Why am I going into such detail? I think it is important to share techniques for using the numismatic research tools. I spent over 100 hours putting up Münsterberg a decade ago and I haven't gotten a single question about using it. I can think of many simple improvements (dropping the lower case Greek letters comes to mind!) and extensions. No one in my circle seems to make them to me.

What tools are people using to identify coins? What do you like and dislike about them?

snible.org should be back

snible.org should be back online. It is now hosted by Amazon.

snible.org will be back soon

My web site snible.org is down. I hope to have it up again tonight. Until then, you may access the AWS mirror.

It was not hacked. The operators shut it down because it went over quota. It is apparently under attack by a virus.

Collectors have the opportunity to comment against Cypriot import restrictions

Ancient coins struck in Cyprus before 235 AD cannot be imported into the United States unless they have an export permit from the Government of Cyprus or documentation they left Cyprus before July 16, 2007. It is believed that no export permits are granted for coins. So American collectors can typically only buy coins from US-based dealers.

This policy, the “Memorandum of Understanding” between the US and Cyprus, is up for review. The Ancient Coin Collectors Guild is suggesting collectors send public comments to the US Government by September 30th. Our hope is that if enough pro-collecting comments are heard a way will be found for some categories of Cypriot coins whose history cannot be tracked before 2007 to enter US collections.

I object to coins appearing in the Memorandum between my government and Cyprus. It is not because I hate all regulations! I object to it because a 100% ban for coins that lack pre-2007 publication means there is no motivation for collectors, archeologists, and the people of Cyprus to have a dialog on different rules that would let us work together.

To me it is obvious that medium-cost export licenses combined with cash rewards for reporting unlicensed antiquity exports would put a halt to the problem. If I don’t object to a simple renewal of the MOU there won’t even be a chance to for folks such as myself to even propose something different than the blanket ban.

If you think ANYTHING other than a blanket ban on coins is appropriate please leave comments asking for coins to be reconsidered in the renewal.

The gorgons of Mallos part 3

Antiochos IV, Uncertain mint (Mallos?), 175-164 BC
(Münzen & Medaillen Auction 30, May 2009 “Roland Müller collection”, lot 706) 1.56g 11mm

Web sites and reference books for Greek coins group the coins by city. For example, Wildwind.com's Mallos entry contains the coins struck under the authority of Mallos.

The typical arrangement skips over coins struck under the authority of a king and used in the city. For Mallos Wildwinds shows nothing for the centuries between a stater of Balakros (struck some time between 333 and 328 BC) and coins of Caligula (struck AD 37-41). Coins issued from 328 BC to 100 BC at Mallos will be hiding in catalogs of Seleukid coins.

The coin at the top of the post depicts a side view of Medusa. The reverse shows Nike standing left holding wreath. Arthur Houghton and Catherine Lorber and Arnold Spaer place the type under the mint at Mallos. [SNG Spaer (1998), p. 150 #1006]. They connect Medusa to the aegis of Athena Magarsia, not to the earlier tradition of gorgoneions at Mallos.

The Gorgons of Mallos

• Part 1
• Part 2

It will soon be difficult to sell autographed slabs in California

David Siders reports for the Sacramento Bee that California Governor Jerry Brown has signed a law with a lot of new requirements for selling autographed items (such as books and coin slabs) in their state.

The bill was promoted by Assemblywoman Ling-Ling Chang, and Jedi Knight Luke Skywalker. The full text of the law is here and I could not understand it. I I have seen nothing about this law on numismatic trade web sites.