Jeremy had more or else ruled out amethyst, but I still love the idea.
Saphire packs a punch but I would have to choose the paint carefully to avoid a red, white & blue look.
I've been loving emerald green lately. I think it could work but again I would have to pick the perfect shade that was deep enough to not read as Kelly (too Christmasy with the red/organge brick) but not too dark as to come off as Hunter (ick).
Another strong option is a deep teal - probably closest to an Apatite. I would likely use the exact color of my gallery photo frames (seen here) .