GRANITE JUBILEE

 A granite jubilee is a hypothetical or symbolic name for a 90th anniversary or 90th milestone.

Key Milestones Compared

Silver Jubilee: 25 years

Golden Jubilee: 50 years

Diamond Jubilee: 60 years (or 75 years)

Platinum Jubilee: 70 years

Oak Jubilee: 80 years

Granite Jubilee: 90 years

Centenary / Centennial: 100 years

Because reaching a 90-year mark for a human lifespan or a traditional institution is rare, the term is largely theoretical.