What kind of costs are we talking about for a conclusive analysis?
If they are a variety of modern "white metal" then it an easy task. Buy a forgers
cast coin, buy an authentic example of the
type (control) clean a surface on each and conduct XRF analysis of the cleaned surfaces. All up cost, including coin purchases probably $500-1000 (note: I have no recent experience in analytical costing so it could prove to be more or less depending on lab/country and cost of coins). If the forger/faker has attempted to truly replicate ancient
billon then detailed trace element analysis of both coins by destructive assay may be required to establish the modern and ancient trace element fingerprint. More costly by perhaps a factor of three depending on what is required by way of accuracy and trace element fingerprinting.
A metallurgist on CFDL made some observations on one coin and believed it to be most probably modern white metal rather than genuine
billon.
A CFDL chemist made observations on the fake nature of the
patina, encrustations and adhesions.
These observations are before the difficult to conceive composition of the
hoard and anomalous differential wear aspects are considered.
I won't repeat these here, as I am not the expert.
Suffice to say a lot of specialist expert opinion exists to suggest these may be modern rather than ancient casts.
Remember, when
buying "genuine ancient"
cast forgeries the issue around authentication must be taken to a much higher level, than with an "authentic ancient"
struck coin, particularly in the context of purported "ancient" casts of the
billon variety. It is easy to determine the existence of a
subaerate core in the case of ancient forged silver, but with
billon forgeries that is an entirely different matter because the forger is not attempting to arbitrage base metal for silver.
Knowingly buy an "ancient"
cast fake with the identical characteristics of a modern
cast fake and the risk of getting burned is higher than ever.
Caveat Emptor (as we noted at the outset).
Something to think about: If you have made a bunch of
cast fakes, how do you most easily move them into the market en masse?
However, for those who feel compelled to own an "genuine" ancient forger
hoard coin, this is probably as
good as it gets and I wouldn't get in the road of anyone so inclined to believe that is what they are purchasing. Rather, I've come to the conclusion that on the
weight of probability they are of very uncertain if not dubious authenticity. As David Sear notes "There is no doubt that these coins are
cast forgeries. The only question that remains to be settled is whether or not they are ancient."
You pays your
money and you takes your
choice, if you are so inclined.