Two SURE ways to sex blue rams....the black spot on the male will have NO blue in it, the female's black spot will have some blue mixed in. The male may also have no black spot at all. Also, look at the dorsal fin (top)...the first couple of fins will be onger than the rest on a male, the females will have a couple of shorter fins first.
As for color, the biggest things are temperature and ph. In a tank at 6.4ph and 84 dergrees, the rams will have amazing color. Look at my avatar...that is one of my male breeders.