Fakes & Wisdom of the Crowd

sulla80
37 minutes ago
9 min read

Fakes removed from my collection with thanks to help from in "Amentia" identifying them. — Fakes removed from my collection with thanks to help from in **"Amentia"** identifying them.

It is said that there are three kinds of ancient coin collectors:

Those who admit to having purchased fakes.
Those who have purchased fakes and don’t admit it.
Those who have purchased fakes and don’t know it.

I generally prefer to focus on history, coins, and art. But a January purge of suspicious and counterfeit pieces from my own collection prompted me toshare my lessons learned. After enough years, every collector ends up building a “black cabinet” - a tray, a drawer, a box - where lessons live. Some of mine were bought deliberately as study pieces. A painful minority arrived in my trays as ambition outran caution.

The story that follows, also triggered by an exhibition of Sicilian coinage at the Archäologisches Museum der Universität Münster, extended into March due to its popularity, offers a timely reminder: experience helps, but transparency and many eyes are now our best defense against sophisticated fakes. At the center is a collector, Hermann Twiehaus, whose decision to share his collection publicly, and later donate it generously, triggered valuable - if uncomfortable - peer review. I tell it with both admiration and sympathy.

Two definitions up front: throughout this post, I use “fake” or "counterfeit" for coins with strong documentation (die identity to published forgeries, casting/transfer diagnostics, or equivalent), and “suspicious” for coins that look wrong but await confirmatory work.

This post has two halves. First, the Münster story - how visibility triggered peer review. Second, a practical checklist and reading list I wish I’d had earlier. Along the way, I’ll acknowledge a personal debt: I have benefited directly from internet collaborators who helped me recognize deceptive fakes I initially missed, and remove them from my collection. See opening photo for the results of my January purge - with many thanks to "Amentia" for his outreach and advice.

A Public Gift

On 19 Jan 2023, the University of Münster announced that its Archäologisches Museum had received a gift of 1,400 Sicilian coins in gold, silver, and bronze, dating broadly to the 5th-3rd centuries BCE, from the Cologne collector Hermann Twiehaus (the museum later lists him as born 1937).

The announcement was framed exactly as collectors hope such stories will be framed: the deed of gift explicitly committed that the coins would be researched and exhibited. The museum director, Achim Lichtenberger, praised Sicilian Greek coinage as among the highest-quality issues of antiquity, and noted that the donation tripled the museum’s stock of ancient coins.

Twiehaus himself said the quiet part out loud - the private collector’s dream of public afterlife:

“Meine Münzen sollen nicht in irgendeinem Safe verschwinden. In Münster sind sie gut aufgehoben.”

“I don’t want my coins to disappear into some vault. In Münster, they are in good hands.”

Photographers captured the signing; a press release hailed an “antiken Schatz" ("Ancient Treasure").

The Passion

Twiehaus was not an anonymous accumulator.

Back in 2016, MünzenWoche profiled his online catalogue as an example of a private collector using the internet to make objects in private hands accessible. It describes him as fascinated with ancient Greece since childhood, collecting early, and eventually focusing his collecting on ancient Sicily; in retirement he catalogued his holdings online so anyone could consult them, free of charge, with bilingual descriptions and high-quality photos.

The same piece notes another detail that becomes important later: he welcomed feedback to correct possible errors. Even the structure of the catalogue hinted at a collector alert to the authenticity problem: the site’s taxonomy included a category labeled “<FAKE>.” (http://ancientsiciliancoins.com/)

None of this guarantees authenticity. But it strongly suggests good faith - and it sets up the second act.

Early Signals

The internet has a long memory. In January 2016—years before Münster—Italian collectors on the forum LaMoneta were already discussing Twiehaus’s online catalogue.

A user introduced it as a substantial private collection of Greek coins of Sicily, noting that one could find the “famous and discussed aureus of Stiela” - a coin whose authenticity had long been questioned in numismatic circles - and adding, “…ecco dove era finito…” (“so that’s where it ended up…”). (Lamoneta.it)

The tone was appreciative but cautious. In the same opening post, the author praises the initiative and then writes the line that should probably be engraved on the inside lid of every coin cabinet:

“Ovviamente ci sono esemplari sui quali non posso mettere la mano sul fuoco…”

“Obviously there are specimens for which I cannot put my hand in the fire”, as one expert delicately put it. (Lamoneta.it)

That is: admiration, plus an early recognition that something in the corpus felt unsafe.

The Crowd‑Sourced Audit

As the Münster announcement raised visibility, the wisdom of the crowd descended. On 30-Jan-2023, the veteran German forum member “Amentia” posted to his thread titled “Fälschungen - diskutieren und zeigen” and began uploading side‑by‑side shots: a Demetrios tetradrachm whose dies matched a piece condemned in Ilya Prokopov’s Modern Forgeries of Greek and Roman Coins; a Syracusan decadrachm exhibiting the blurred “transfer‑line” of a cast fake; a whole run of staters traced to an eBay seller named “Filippo". Within hours other users piled on, noting off‑weight flans, ghostly seam marks and mismatched styles - evidence collectors learn to spot but that can elude even seasoned collectors working in isolation.

The Münster press release did two things at once: it celebrated a gift and it amplified visibility. The university itself pointed readers to the donor’s digitized catalogue.

Soon after, collectors on German-language forums began combing through the images with renewed attention. In a Numismatikforum thread, the user “Amentia” wrote (in essence) that after reviewing the online catalogue he found many forgeries and suspicious pieces, despite the donor’s decades of experience = “a real shame,” especially because some “showpieces” seemed to have come from unreliable sources.

"It was reported in Münzenwoche that the University of Münster received a donation of a collection of ancient Sicilian coins. I went through the collection and unfortunately found many forgeries and suspicious pieces. The donor appears to be an expert in these coins and has over 50 years of experience with ancient coinage - and yet, there are so many fakes included. That's a real shame, because it seems that many of his absolute showpieces were purchased from unreliable dealers."
-Amentia in Numismatikforum (translated from German)

This is the double edge of digitization: it is not only an exhibition, it is an invitation to peer review. And in numismatics, “peer review” is often visual, comparative, and fast:

style that doesn’t fit a mint or engraver’s hand,
surfaces that suggest casting or transfer techniques,
weights and flans that don’t behave like the series,
and - most decisively - die identity with known modern products.

What makes the episode unsettling is not that mistakes happened—mistakes happen to everyone - but that they surfaced in a collection assembled over half a century, by someone publicly described as having acquired extensive knowledge.

In a hobby where ew like to believe that “experience protects you”, the Münster story is a reminder that experience is necessary - and still not sufficient.

Second Act: from discomfort to instruction

For museum's numismatists the episode proved both embarrassing and instructive. Students preparing a 2024 exhibition suddenly had a live case study in authentication science: die‑link analysis, metallography, even magnetic‑susceptibility testing (a technique publicized in the Jahrbuch Kölner Münzfreunde the very year the news broke).

Curators re‑catalogued suspect pieces and promised a future scholarly report that would separate wheat from chaff - turning a donor’s misfortune into a teaching moment about provenance, expertise and the rising tide of “super‑fakes”. In 2025/26 the Archäologisches Museum mounted the major exhibition “Sizilien - Insel der Arethusa” (8 Nov 2025-27 Feb 2026). The museum text explicitly notes that it is unusually well-stocked in Sicilian coins because of private donations, and places the show in the Fürstenberghaus at the Domplatz.

Crucially, the exhibition text does not pretend the market is clean. It states that the popularity of Arethusa coins as collectibles is demonstrated by “numerous forgeries - some grotesquely wrong, others nearly perfect".

The companion booklet (a 68-page publication cataloguing 420 exhibited coins) explicitly includes an essay addressing the problem of coin forgeries.

And the museum did not erase provenance. A February 2026 “Münze des Monats” entry describes an Arethusa decadrachm and records it as part of the museum’s own coin collection with inventory number, marked “ex Slg. Twiehaus” (from the Twiehaus collection).

Even the public response to the exhibition became part of the record: the museum later reported that the show drew roughly 5,300 visitors in four months and was extended to 27 March 2026 because of sustained interest.

The University chose to make authenticity, collecting, and forgery part of the education, rather than a footnote.

Practical Conclusions

The Twiehaus story a raises a number of practical lessons

the value of digitizing collections to empower & engage an informal, borderless peer review
the sophistication of modern forgeries that can pass undetected (even experts)
institutions must combine gratitude with due diligence when they accept private collections

Hermann Twiehaus's collection & generous gift will certainly educate future generations on Sicilian art and numismatics. It also gives an important window into the dark side of the ancient coin world, the pervasiveness of deceptive fakes, and the value of the online communities in sharing expertise.

So what can you do?

Be aware of these visual clues

The more obvious fakes are cast, leaving specific evidence

Soapiness: Authentic coins have sharp details (unless worn smooth). Cast fakes often look "soft," "mushy," or "soapy," as if the coin was made of melting wax.
Air Bubbles: Look closely at the surface carefully (full magnification online). Casting often leaves tiny holes or craters where air bubbles were trapped in the mold. Struck coins shouldn’t show casting bubbles; pitting from corrosion is a different phenomenon
Seams: Check the edge of the coin. A cast coin often has a seam running along the edge where the two halves of the mold met. Forgers often file this down, leaving tell-tale parallel file marks on the edge.
Perfect Roundness/Strike Evenness: Ancient coins were handmade and often have irregular, oblong shapes. Perfect roundness plus uniformly modern edge/finish can be suspicious - context matters by series and period.
Weight: Ancient mints were very specific about weight standards (e.g., an Attic tetradrachm should be roughly 17.2g). If a coin is significantly under-weight, it might be a cast made of base metal or a plated fake. Always check the weights reported in auctions.

Ancient silver often "crystallizes" over 2,000 years, making the coin brittle. If you see crystallization at the surface this can support a call of "genuine" - although this is also a sign of a coin that could break easily or is less desirable.

Before you buy

"Know the dealer or know the coin". If you can’t do one, do the other - ideally both.
Treat “high-risk areas” as a separate skill set. Most of the fakes I bought came from eBay, in categories that are saturated with modern forgeries, and I was often learning the series as I bought. That’s a predictable way to get burned.
Don’t assume “reputable” venues are immune. My most expensive fake didn’t come from eBay - it came from a respected auction house.
Learn to recognize die matches. This post from @dougsmit can be a fun place to start : https://www.forumancientcoins.com/dougsmith/dielink.html (it comes with a test). Being able to see a die match is essential to recognizing your coin as a die match to a known fake,

This map of obverse / reverse pairing from "Amentia" is an impressive die study of the Philip V triobol fakes.

After you buy

Act quickly - especially while returns are still possible. A reputable dealer will generally refund the purchase price and/or help resolve authenticity concerns. If they won’t engage, the label “reputable” isn’t deserved.
Accept that some lessons can’t be refunded. All of the fakes pictured above had been in my trays too long for any recourse. At that point, the only option is to absorb the cost and file the coin - literally - in the black cabinet.

Contribute

Share expertise. No one can be expert in every series, and general collectors are more vulnerable than specialists. Posting coins, asking questions, and offering careful opinions improves teh system for all of us.
Report confirmed fakes. When you can document a forgery, reporting it - whether to auction houses, databases, or “fake seller” lists - helps remove bad material from circulation faster.