1 Crown - Elizabeth II Platinum Wedding - Cathedral, Gold

Tristan da Cunha is a British Overseas Territory in the South Atlantic with no airport and a permanent population under 250, yet it has issued commemorative coins continuously since the 1950s — almost none of which ever circulate on the island. This piece marks the 2017 platinum wedding anniversary of Elizabeth II and Prince Philip, their 70th.

The .375 fineness — 9 carat — keeps production costs low enough for the small-weight collector market that drives these issues.