What color primer under Plum Crazy

My car is a burnt orange/copper color (made it myself, ain't come up with a name for it yet though...). When I had to repaint it, I wanted it just a touch darker. Layed down a coat of black before starting on the orange, car turned out lighter... Still looks great, just went on to dumbfound me on how colors actually work. Guess I wasn't born to be a rocket surgeon.