8 Reales "Birmingham" Forgery 1794?

A "Birmingham" forgery would be a contemporary counterfeit and the date and mint would have been carefully chosen to blend in with other circulating currency. The Santiago mint would be a terrible choice for such a coin. This is likely to be a modern forgery and thus nearly worthless.

I agree this appears to be from the GNL Book on page 311 the GNL variety = GNL#1794-O:Aa/R:So Da-001. Sheffield plate probably on a brass or more likely IMO on a copper alloy. Sheffield plates are normally on copper alloys irrespective of what we wrote on page 311 in 2014. English counterfeiters preferred a copper host whereas with French silver plated coins they preferred a brass host instead or the so-called French plating process. Use the Heritage site of auction archives of George III 8R countermark specimens and determine if this countermark is real - remember here you have two possibilities - a fake countermark on a fake host (more likely) or a "real" countermark on a fake host (less likely).

John Lorenzo
Numismatist
United States