Simplify the following text for a Grade 5 native English-speaking person.
Original: A Diamond Jubilee is a celebration held to mark a 60th anniversary in the case of a person ( e.g. wedding anniversary , length of time a monarch has reigned as King or Queen , etc. ) or a 75th anniversary in the case of an event .
Simplified: A diamond jubilee is a celebration of a 60th anniversary for a person . When for a group , it is used for the 75th anniversary .