A platinum jubilee is a celebration held to mark an anniversary.
[1] The most recent monarch to celebrate a platinum jubilee is Queen Elizabeth II of the United Kingdom and the other Commonwealth realms in June 2022.
The celebrations were delayed from the actual February anniversary and the ceremony occurred on a four-day Bank Holiday on 2 June 2022, as was announced earlier.
[3] Elizabeth II died on 8 September 2022, three months after the official celebrations in the Commonwealth took place.
[9] An anniversary of 100 years is simply called a centenary.