Prince's Top Secret Memorial ... If You Make the Cut

A celebration for Prince is going down in Beverly Hills Wednesday night, but almost no one's heard about it ... unless you were a legit member of his inner circle.

A source who was VERY close to the singer tells TMZ they received an invitation that only mentioned the time, date, and city for the "Celebration of Life." The source was told to pass the word, but ONLY to the most important people his Purpleness would have wanted to attend.

One of Prince's family members says they didn't hear about it, so it appears this is exclusively for close friends and people in the biz. We're told the exact location is only being revealed to invitees who get vetted after RSVP'ing by email.

Bottom line: There are about to be some disappointed people who thought they were tight with Prince.