I had asked David about how someone could identify a later striking of a medal by the French Mint. Apparently they will stamp out a medal for you if they still have the dies available. Since price is often a function of rarity, a restrike that was indistinguishable from an original struck me as something of a fraud. His answer in part included the following tidbit:

   In regard to the later medals from the French mint, in 1830 they began edge-marking silver and gold medals, whether old or new. In 1842 they began marking copper or bronze medals as well. At first only a tiny symbol was punched in, then the name of the metal was added.

   During Napoleonic times the 'bronze' medals were made of copper; an artificial chocolate patina was added to them. This patina was made from a naturally occurring pigment from a mine to which apparently only the Paris mint had access; the director of Napoleon's Italian mint complained that he couldn't get it. It seems that the source ran dry; after 1830 the Paris mint tried various other artificial patinas, which betray the copper or bronze later but unmarked before 1842 strikes. The mint played with copper versus bronze at about and after that time; you will find nineteenth century strikes marked cuivre and strikes marked bronze. Later in the century chemists found how to duplicate the chocolate patina, so it reappears, but by that time the edge marks were in use, so there's no problem there.

   The original chocolate patina was applied to the struck up medal by dusting on a finely divided pigment plus binder. The medal was then returned to the press, where pressure and heat fused the coating on.

   With the precious metal medals there is usually a 1 or 2 for first or second quality. I think silver is 95% or 80%; I don't have the figures for gold. Today the mint is adding on the edge the year struck.

   David has since put together a page describing how the edge marks work. I suggest you take a look if you have a Napoleonic era medal with edge marks.