It's a beautiful ring - sparkly gorgeous princess in a classic, elegant setting. Is there any place (restaurant, park, etc) that has special meaning to you and your gf? You could propose there. Please come back and let us know how it goes and post hand shots if you can.
The ring is beautiful, i'm sure she will be floored!! I second the motion to check out the proposal idea forum. Lots of guys with interesting ideas over there! Good luck to you!
I think a romantic picnic is always nice for a proposal. My husband proposed on top of a mountain after we rode the lift to the top. I loved it. It was nice to know he put thought into it and picked a place that was special to both of us.