It's beautiful. Why not ask your friend what she'd like? Maybe a dark wine red? I mention that because one time I was getting ready to repaint a mantel in a house where someone had previously painted everything a neutral. I agonized over the color and asked a friend whose artistic sense I admired. She ignored my various options (gray, black, etc.) and said "dark wine red." We did it, and loved it! I happen to think it would set off your medallion very nicely.