5 Pounds - Elizabeth II Duke of Edinburgh, Gold Proof

Issued to mark Prince Philip's 95th birthday, this coin appeared during what was then the longest marriage in British royal history — Philip and Elizabeth had been married since November 1947. Guernsey, as a Crown dependency, issues its own coinage independently of the Royal Mint, giving it latitude to produce commemoratives on its own schedule and to its own specifications.

The .9167 fineness matches the traditional 22-carat standard used for British sovereign coinage since the Tudor period.