Prince: Unreleased Music Debuts ... Gift to Donatella Versace

It could be a first glimpse into Prince's fabled vault of new music, and it premiered at Milan Fashion Week ... courtesy of Donatella Versace.

Donatella cranked the 11-minute mix during Saturday's show of Versace's men's collection. She says Prince, who was a longtime friend, would send her music all the time as a way of communicating.

It's unclear if Prince's estate approved the untitled music being used by Versace -- or if it would even need to do so ... if Prince had gifted it to Donatella.

Check out the music -- you gotta wonder if Prince would be happy it's gone public.