From Longman Dictionary of Contemporary Englishdiamond jubileeˌdiamond ˈjubilee noun [countable] TMCthe date that is exactly 60 years after the date of an important event, especially of someone becoming a king or queen → golden jubilee, silver jubilee
Examples from the Corpus
diamond jubilee• In 1968, the diamond Jubilee came and went without celebration for fear of a financial loss! 