Ed Snible has this thought-provoking post on his blog: http://digitalhn.blogspot.com/
It would be interesting to hear what others think, particularly any coin dealers out there. Coin dealers tend to have very large inventories. Even smaller ones can have 10,000-20,000 coins on hand at any given time. Given the numbers, I suspect many of them will consider this plan to be impractical. On the other hand, if there is demand for "registered coins" won't there be a financial incentive to supply them to the marketplace?
Registering coins would presumably be easier for collectors. Collectors tend to hold hundreds not thousands of coins. Still, registering even that number could be both time consuming and at least somewhat expensive. Nevertheless, such registries could also be used for insurance purchases.
Overall, any plan of this nature would probably need some form of government blessing. Very few will undertake such a task without it. Of course, under current law, date stamping a picture of a coin today won't help you much to prove a coin of Cypriot type was out of the country before import restrictions were imposed last year.
And what of the archaeological community? The AIA and other archaeological organizations seem stuck on idea that the ownership history of any artifact must be traced back almost 40 years to 1970 before they will (with some reluctance) consider it "legitimate." Obviously, registering a coin today will do little to assuage ideologues hung up on a 1970 date based upon when the UNESCO Convention was promulgated.
One final thought. Why not also require archaeologists to use an identical system to record coins found at excavations? At the very least, registries of coins from all sources would give us some idea of how many ancient coins are actually out there.
Despite my concerns, I think this idea merits serious discussion.