Silversilk by Christine Morgan

Twenty years of war between the elves and the dwarves have left the Emerin a land without a king. The only way to find one is to seek out the Emerald of Karria, a fabled jewel. But the Emerald rests in a hidden temple, and only a king or a swordmaiden can handle it safely. And in Emerin, swordmaidens are unheard-of.