The Collaborative International Dictionary of English v.0.48:

Prettiness \Pret"ti*ness\, n.
   The quality or state of being pretty; -- used sometimes in a
   disparaging sense.
   [1913 Webster]

         A style . . . without sententious pretension or
         antithetical prettiness.                 --Jeffrey.
   [1913 Webster]

WordNet (r) 3.0 (2006):

prettiness
    n 1: the quality of being appealing in a delicate or graceful
         way (of a girl or young woman) [syn: prettiness,
         cuteness]