1 Crown - Elizabeth II Tynwald, Platinum Proof

The 1979 Tynwald Millennium crown commemorates a thousand years of the Manx parliament, one of the oldest continuous legislative assemblies in the world — the annual open-air sitting at Tynwald Hill in St. John's is a constitutional requirement, not ceremonial theatre. Pobjoy struck this issue in four metals, with the platinum version limited to just 30 pieces.

At 52 grams of .950 platinum, the production cost alone was extraordinary for 1979, when platinum briefly exceeded $900 per troy ounce during the Iranian Revolution-driven precious metals spike.