The first, and only for many years, stamp  Zlobenia was the One Zloty from the Year of the Signifying Frog.  Essentially is shows the arms of the principality, which features its  largest export - clogs - on a shield held by an eagle.

The stamps were  printed in sheets of 32, and there was just one sport per sheet. This was a hard one to spot, with the eagle’s feet, normally white, solid black. The selvedge decoration is unique in having partial rubber stamps of the coat of arms in red. The text tells us that the stamps were printed by royal appointment in Zlobenia - the first Discworld stamps not to involve Teemer & Spools.

To accompany the stamps there was a Consulate cover and a proof sheet. This proof was produced for Royal Approval (Prince Heinrich) and has two panels of six stamps; one panel of commons and one of sports. All text is written in Zlobenian thus we learn that sport in that language is “sportebastarden€”. Intriguingly there was an alternative version with yellow, rather than blue, ornate surround,  and all text in English (or Morpokian perhaps). Were both on sale, or did the  Morpokian version get pulled well before release date?

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There are some Imperial Russian stamps that bear a striking resemblance to the 1 zloty, like the 20 kopek stamp shown. Just how the Russian designer managed to anticipate the Zloblenian 1z stamp in order to create his own version is not known, but quantum is probably involved. He is probably long dead so unable to comment. (There are other examples on the Doppelgangers page)

And in an attempt for completeness here, a 1 Zloty stamp appeared on one of the Mrs Cosmopilite letters. This was one of four covers that were a free gift with a purchase of Lu-Tze's Yearbook of Enlightenment - 2008 Diary from the Discworld Emporium