don't breed for diamond eye or pearlscale... Diamond Eye is blindness caused by a buildup of dragon scaling over the eyes. NOT something you want to breed for. Pearlscale is done by one breeder only so far, and because it's so new, it's not even known if it's something you SHOULD breed for.
Marbles are pretty rare, outside of breeders. Butterflies aren't seen that often in the more unusual colors.... true Orange isn't seen too often(i'm talking orange, not light orange. not salmon. not kinda orange. Orange like my Zidane was: http://chibichii1987.deviantart.com/...16073411&qo=16
yellow is pretty uncommon, as well.