Thursday, February 01, 2018

Recording provenance in the blockchain

An October 2017 article by Peter B Campbell in The Guardian, “Archaeology and blockchain: a social science data revolution?” discusses using blockchain, the computer technology that ensures Bitcoins are not counterfeited, to record provenance data for antiquities.

Campbell is an archeologist and his article mentions Islamic State and blood antiquities. Those claims might be overblown but the technical scheme described by the article seems workable for medium and high values items. The startup Kapu already conducted a test of using a digital 'coin' to create a provenance ledger.

Were an artifact to have a blockchain record, each time it crossed a border or was sold to a new collector the record could be updated to show it was legitimate. Conversely “blood antiquities” would have no record and faked records could not be manufactured as they often are today. Border security could then compare records of artifacts declared at customs to databases such as INTERPOL.
Some of the ideas, like swabbing antiquities with synthetic DNA, seem fanciful. The basic claim seems solid. Using blockchain technology for art isn't science fiction. An article by Jason Bailey on Artnome explains that the technology is already in use for proving ownership of digital artworks. Verisart and Codex are startups in this space. They hope to convince auction houses to use their technology to record sales.
Codex Protocol is designed as industry infrastructure for art and collectibles. So it's fine wine, classic cars, jewelry, fine art, anything else that sort of fits into that category of items.
For ancient coin collectors one problem is that we would like to be able to prove ownership before 1970, or before the 2007 agreement between the United States and Cyprus. These technologies are for recording transactions now, not 50 years in the past. I would be interested to learn what the legal community thinks of these things.

The SciTech Lawyer, a publication of the American Bar Association, just published an article on that very topic. Unfortunately for me, law professor Derek Fincham's article “Can Blockchain Technology Disrupt the Trade in Illicit Antiquities?” is not available to non-subscribers.

In the comments section, discuss if you would be interested in using blockchain to record your ownership of coins, and if you would pay a premium to know the previous owners of a coin back to 2019.

Monday, November 13, 2017

Himyarite coin with ancient South Arabian script

Unicode has included letters for the ancient South Arabian script used in Himyarite coins for a long time but I have never seen them used except in sites about Unicode itself.

Here is a coin from mint 𐩧𐩺𐩵𐩬 (=RYDN, Raidan/Raydan, at Zafar in Yemen).

I am not sure what is needed to use South Arabian script on your computer. I have a nice font of them on Mac OS 10.12 rendered under Safari but not under Chrome or Firefox.

The mint name, Raydan, is encoded as follows:

𐩧 = R
𐩺 = Y
𐩵 = D
𐩬 = N

I had more difficultly with the name of the ruler. It is 𐩲]𐩵𐩬𐩽𐩨𐩺𐩬 (= ʿMDN BYN, Amdan Bayyin Yanuf). Two of the letters on the coin did not make sense.

𐩲 ?= is this ʿ (Ayn, the rough breathing mark)?
] ?= I couldn't find this one in the table
𐩵 = D
𐩬 = N
𐩽 ?= This looks like their digit 1, but I couldn't find any reason it appears here.
𐩨 = B
𐩺 = Y
𐩬 = N

HIMYARITES. ‘Amdan Bayyin Yanuf, 2nd century AD. AR Scyphate Quinarius (1.16 gm) of Raidan mint. 13mm Obv: Male head right, within torc Rev: Himyarite/Sabatean legend 𐩲]𐩵𐩬𐩽𐩨𐩺𐩬 ʿMDN 1 BYN 𐩧𐩺𐩵𐩬 RYDN; Small male head, monogram to left, scepter symbol (or monogram?) to right. Ref: Sear, GIC 5717. Munro-Hay 3.2ai. ex-Pegasi Numismatics, Auction XXXIV, May 2016, lot 243 (unsold)

I don't actually have Stuart Munro-Hay's book Coinage of Arabia Felix so I have been using his article “The coinage of Shabwa (Hadhramawt), and othe ancient south arabian coinage in the national museum, Aden” which is available online and includes information on inscriptions.

I would be curious to know which computer/browser combinations can see the ancient South Arabian characters above. I would also be curious if anyone knows the correct Unicode way to encode the letters I am uncertain of.

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.

Tuesday, August 29, 2017

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.

Monday, July 17, 2017

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.

Saturday, July 08, 2017

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.