This could also be titled, The Girl with the Gem in her Navel.  Every 100 years, God bestows a godstone (gem) in the navel of an infant chosen to do something magnificently heroic.  Sure, that sounds a bit odd, but it works.  I immediately liked the godstone-bearing princess.  She is the second daughter of a king and finds herself betrothed and quickly married off on her 16^th birthday, to a king that she has never met.  She is a pawn in the political game.  Both countries face the same adversary.  Princess Elisa starts out rather overweight , apathetic, and not comfortable with her role as godstone bearer and not at all sure of her relationship with her handsome new husband.  However, around every corner she finds her life and the lives of her friends, threatened.  She rises to the challenge every time.  Plenty of betrayals spice up the action-packed novel full of kidnapping, rebellion and fighting.  This is the first in a planned trilogy and I will eagerly read them all!