1 Cent

Redonda is an uninhabited volcanic rock in the Caribbean, roughly one square kilometer, claimed as a kingdom by a succession of self-appointed monarchs tracing back to a 19th-century literary joke. The "Kingdom of Redonda" is a fiction maintained by a rotating cast of British writers and eccentrics — M.P. Shiel, John Gawsworth, and Jon Wynne-Tyson among them — who awarded noble titles to literary friends as a kind of elaborate in-joke. This coin has no circulating economy behind it, no subjects to spend it, and no treasury to issue it from.

The X# prefix in the Standard Catalog places it squarely in the "Unusual World Coins" category — fantasy and private issues.