Very interesting and rare in such a good condition forgery of the so-called mint forgery, defined in this way by Grzegorz Romanczyk, the author of the specialist catalog of groschen of Zygmunt I.
The stamp of the presented coin is fully correct and original, but corrosion and rust speak for mint forgery. Forgeries of this type were characterized by the fact that they were planchet with a very low content of silver in the alloy or only coated with silver. They were minted with original dies at the mint or by mint workers.