Apparently, they have some Playing Card Motif..
I swear that there's some similarities to Shugo Chara already, if you
know what I mean.
Thinking about their PreCure names, they really have some meaning that probably describes their characters..
Heart = The obvious; Heart, love, (pure) feeling(s).
Diamond = Symbol of love.
Rosetta = Rose flower, or
Beautiful Rose in Italian..
Sword = Chivalry, Courage, Determination, Protection, Strength, Truth, Love..
Having a feeling that Cure Rosetta is going to attract plenty of guys.