What to get for my GF's birthday?

On my birthday my GF got me a Ferragamo Wallet which is around 400USD. Now it's my turn to give her a birthday present, I kinda have a rough idea what I might end up giving her, but still, I would like to get some more advices. The cost should be no less than 400 but no more than 700. (I am not the kinda guy that spend their parents money to buy expensive things, therefore that would be the budget limit.)|||Jewelery. Pearl necklace, or some diamond earings.|||A Pearl Necklace is always a fine gift.