On May 30, 2020, Dr. Jonas Flueck of Ex-Numis (https://www.ex-numis.com/page/about.html)
and Lugdunam International Auction House (https://www.lugdunum-numismatik.com/en/)
explained his use of facial recognition technology to rediscover old
provenances for ancient coins. United
States import restrictions imposed on ancient coins, new regulations in Germany
and the EU, and claims that terrorists have been selling ancient coins to fund
their activities have all made the rediscovery of old provenances more
important than before.
Dr. Flueck
prefaced his talk with a discussion of different types of provenances. Provenance is generally comparable to the
concept of chain of custody. The
International Association of Dealers in Ancient Art has developed useful
concepts to explain different forms of provenance. “Hearsay provenance” is the weakest form of
provenance. This is a vague provenance,
usually restricted to a date or location.
An example is “from an old Swiss collection.” The only thing that backs up this provenance
is the good faith of the dealer in question.
“Named provenance” is somewhat stronger.
It is a provenance linked to a specific collection or person. The problem is that this kind of provenance cannot
always be verified. The strongest form
of provenance is “documented provenance” linked to a specific sale or other documentary
material like invoices or export licenses.
It is this last, strongest type of provenance which Ex-Numis seeks to reestablish.
Until
now, dealers and collectors have had to conduct manual searches through
hundreds of old auction catalogues to recapture old provenances. Without some suspicion where a coin may have
appeared in the past, this is virtually an impossible undertaking. The genius of Dr. Flueck’s system is that he
has spent considerable time, effort and money scanning thousands of auction
catalogues and then applying facial recognition technology to compare coins
which are submitted to his service to those in old catalogues in order to
recover old provenances. These include
some 130,000 coins listed in catalogues pre-dating 1970, the date of the UNESCO
Convention.
Still,
the system has some serious limitations that help explain why the vast majority
of coins without a recoverable provenance are not the products of recent,
illicit digs. First, before widespread
use of digital photography in the 1990’s, it was time consuming and difficult
to take photographs of coins. For that
reason, the vast majority of coins sold at auction or in fixed price lists were
not photographed. Second, although
Ex-Numis has recently sought to add fix price lists to its database, many of
these lists were only produced in small numbers and are no longer easily available
today. Lastly, the system does not
capture more recent provenances created during the digital era; however, such
coins can be found reviewing commercially available databases, like Coin
Archives, AC Search, Sixbid Archives or CNG’s Research page.
Notwithstanding
these limitations, when a match is found, it can not only detail lost
provenances but whether a coin has been altered over time by cleaning or
tooling. It can also provide some
assurance that a coin was on the market before the advent of highly
sophisticated fakes produced with the use of laser cut coin dies. Conversely, it can prompt concerns about
authenticity if a coin was previously withdrawn from auction.
Recovering
a provenance can also establish a particular coin was formally in a prestigious
collection, like that of Prof. Pozzi and Sir Arthur Evans, a famous
archaeologist. Moreover, it can show
coins travelling internationally between the United States and Europe. Finally, it can show how prices change over
time for specific coins.
Archaeologists
and others not familiar with ancient coin collecting often ask why so many ancient
coins lack a provenance. First, most
coins in the past auctions were a very small part of the market. Most coins were instead purchased at coin fairs
and in coin stores with an invoice, but one which did not picture the
coin. Second, because provenances were
not that important, they were often not included in auction catalogues, except
for coins from famous collections.
Third, before the advent of modern facial recognition technology, it was
very time consuming to search for old auction provenances by reviewing old
catalogues.
Dr. Flueck
became interested in old auction catalogues when he began work at a Swiss
auction house. Over time, he has collected
a large number of auction catalogues, which he married to facial imaging
technology. This technology works best
for coins with irregular flans, which is common in the Greek series. It works less well with coins with regular flans
made in quantity, which includes most Roman Republican and Imperial coins. It is also difficult to match coin images in
old catalogues produced with the use of plaster casts.
The
process for developing his system was very time consuming. First, he collected a large number of
catalogues based on lists of historic catalogues. He then cut out individual pages and
created PDF pages and then pages individual coins. He ended up scanning approximately 5,000
catalogues to create his database. These
catalogues date from the late 19th c. to about 2005, when most
catalogues went digital. The auctions are from around the world of ancient,
chiefly Greek and Roman coins.
Since
2006, he has rediscovered more than 5,000 lost provenances, which he hopes do
not get lost again. It is easier for the
system to locate coins with irregular flans.
It is more difficult to locate coin images with regular flans, which
includes all early coin images made by use of plaster casts.
Going
forward, Dr. Flueck hopes to add known forgeries and stolen coins to the
database. Such coins can then be
removed from the market and stolen coins returned to their rightful owner.
Dr. Flueck
then answered several questions. He was
first asked if his system could be used for Greek vases. He believes a similar system could be applied
to Greek vases if funding is found.
Dr. Flueck
was then asked if it is harder to find provenances for Roman coins because more
Greek coins in the past appeared at auction.
Dr. Flueck does not have statistics for that because he searches for Greek
coin provenances far more frequently. He
does note however that it is more difficult to find matches or Roman coins
because of their more regular flans.
Dr. Flueck
has not been asked to provide expert legal testimony, but he has provided
provenance information used for export and import paperwork.
Dr. Flueck
asked how fast the database is growing.
He indicates he is at a point where it is difficult to acquire new
catalogues. He hopes to add reference
works providing provenance, major collections that were dispersed privately and
fixed price lists. Of course, this is
also very time consuming. It is noted
there is a dearth of published provenances from the late 1930’s to 1950’s due
to WWII and its immediate aftermath.
The
oldest provenance Dr. Flueck has traced is from the late 19th
century. The most valuable is for a
Dekadrachm of Syracuse.
Fixed
price lists are important sources of provenance information from the
1950’s-1990’s. Dr. Flueck has a complete
set of Münzen & Medaillen and Credit Suisse price lists. Bank Leu and Hess also produced some rare
lists from this period. Dr. Flueck is
missing American price lists from the 1960’s-1970’s from his database.
There
is also a discussion of the American Numismatic Society card file. Hopefully, this can be digitized in the
future. The Schaefer archive will also be a source of provenance information
for Roman Republican coins.
The
database depends on what was considered an “ancient coin” in the auction
catalogues. As a result, there is uneven
coverage of Byzantine or barbaric coins.
Byzantine coins are typically difficult to match because the flan shapes
are so similar.
There
is a discussion of the 130,000 coins in the database with pre-1970 provenance.
Dr. Flueck notes that this relatively low number is attributable to the fact
that so few coins were photographed during this time period and so many were
sold outside of auctions. Even for
auctions, most coins were merely listed, not pictured. Typically only about a quarter of coins may be
pictured.
The
Bronx Coin Club and the Ancient Numismatic Society of Washington, D.C. co-sponsored
Dr. Flueck’s presentation. Dr. Flueck’s
Zoom Video Talk can be found here:
https://www.youtube.com/watch?v=fn_hw9C-o4M&feature=youtu.be
. For more about Ex-Numis, see its
website, here: https://www.ex-numis.com/page/the-idea.html
.
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