I was with the same person for 5 years, from when I was 15 until a year ago.. 2 years into our relationship he noticed me looking at a white gold ring with a pearl on top (it was about $250) for Christmas he got it for me (me not knowing that it was going to be a promise ring) and told me that he loved me, and will always love me no matter what I do or where I go. I don't think that you should get her a cubic z. because it looks too much like a diamond, I think that it should be a simple ring that she can wear everyday, and yes I wore mine on my left hand.. Also do not think that you need to wear something, this is not a marriage, just a gesture of your love to her!!