It is well known that the "Lydian Hoard" returned from New York "was acquired by the Metropolitan Museum over the period 1966-70 from John Klejman of Madison Avenue and the Swiss dealer George Zacos" (Stealing History: The Illicit Trade in Cultural Material, p. 10). The issues surrounding this particular "Hoard" case have been rehearsed elsewhere but Brodie et al. commented about the Metropolitan Museum of Art,
The Metropolitan failed to do the decent thing. Although caught red-handed and with deeply incriminating documentation in the museum's files, it went to court in an attempt to change the State of New York's rules about the period of time in which a claim for stolen property is allowed to proceed, hoping to keep possession. But in 1990 its case was dismissed. ... In 1993 the museum finally agreed to return the Treasure and the lawsuit was dropped.
We do not know - or more accurately, we are not told - how the piece now at Bonham's first surfaced at Sotheby's back in the mid-1970s. Had it too passed through Switzerland? Are there any trading associations with the former New York material? These are issues that must be addressed.
It is clear that the "Lydian Hoard" in general emerged on the market in suspicious circumstances - and it was rightly returned to Turkey. So if a piece of silver - "virtually identical" to one in the hoard - appears on the market and is known to have first surfaced around the time of the "Lydian Hoard", then there are grounds for suspicion.
Do suspicions matter?
Yes. If you read the UNESCO International Code of Ethics for Dealers in Cultural Property which was endorsed in November 1999 (now helpfully reproduced in Legal and Practical Measures Against Illicit Trafficking in Cultural Property: UNESCO Handbook (2006) [pdf]; the code is mentioned in the UK Department of Culture, Media and Sport document, Ministerial Advisory Panel on Illicit Trade (2003) section 104) you will find that Article 1 states
Professional traders in cultural property will not import, export or transfer the ownership of this property when they have reasonable cause to believe it has been stolen, illegally alienated, clandestinely excavated or illegally exported
I presume that Bonham's would consider themselves to be "Professional traders in cultural property". I presume an auction of a piece of Lydian silver could be considered as "transfer the ownership of this property". And given what we know about the "Lydian Hoard" and the clear stylistic association with this silver kyathos there could be "reasonable cause to believe it has been stolen, illegally alienated, clandestinely excavated or illegally exported".
So, some simple questions. "Yes" or "no" would be sufficient for the moment.
Have the staff at Bonham's checked with the authorities in Turkey to ensure that this piece was not "stolen, illegally alienated, clandestinely excavated or illegally exported"?
Have the staff at Bonham's checked the documentation for the history of the piece prior to its sale at Sotheby's in the mid-1970s?
And the answers matter because Article 3 of the UNESCO Code of Ethics states:
A trader who has reasonable cause to believe that an object has been the product of a clandestine excavation, or has been acquired illegally or dishonestly from an official excavation site or monument will not assist in any further transaction with that object, except with the agreement of the country where the site or monument exists. A trader who is in possession of the object, where that country seeks its return within a reasonable period of time, will take all legally permissible steps to co-operate in the return of that object to the country of origin.
Bonham's also need to remember Article 8 which states:
Violations of this Code of Ethics will be rigorously investigated by (a body to be nominated by participating dealers). A person aggrieved by the failure of a trader to adhere to the principles of this Code of Ethics may lay a complaint before that body, which shall investigate that complaint before that body, which shall investigate that complaint. Results of the complaint and the principles applied will be made public.
I presume that in the case of Bonham's it would be the Antiquities Dealers Association (ADA) whose Code of Ethics states:
I agree to conduct my business in such a way as to bring no discredit on the Association or its members or the trade in general.
But I am assuming that Bonham's supports the notion of the UNESCO Code of Ethics. They should, because UNESCO makes a case for why dealers need to take it seriously:
Adopting the Code gives dealers a way of distancing themselves from disreputable people who claim to be dealers and in fact make no inquiry into provenance or even themselves knowingly instigate illegal acquisitions.
It therefore attracts to them the business of ethical collectors and raises the reputation of the ethical dealer community in the minds of the public and the media.
In cases where dealers themselves are selling as owners and not only as agents, it also gives them the right arguments to insist on proper evidence of legal acquisition from their suppliers.
Brodie, Neil, Jennifer Doole, and Peter Watson. 2000. Stealing history: the illicit trade in cultural material. Cambridge: ICOM UK, the Museums Association and the McDonald Institute for Archaeological Research. [pdf]
UK Government documents on the illicit trade in cultural objects
Dealing in Cultural Objects (Offences) Act 2003