100 Francs Tyrannosaurus rex

The Democratic Republic of the Congo has issued gold miniature coins in this format since the mid-2010s, targeting the collector market rather than any circulation purpose — the country's actual currency is the Congolese franc, and denominations of this kind exist purely as legal tender fiction. At 0.5 g of fine gold, the intrinsic value vastly outpaces the face value, which is the point.