Jade is an elemental. Elementals of this world are born from energy around them (Example: A water elemental forms in an ocean, lake, or river, gaining life force and power from the living and moving things around it. Her voice should should sound both ancient and young (Elf-style) and have a spacey-effect (Perhaps almost like the wind itself is speaking). If you have something else in mind, go ahead and try it! I would love to see what you come up with.