Something I wish my bf would do for me is when I come home from work is have the bathtub beautifully lit with candles and rose petals everywhere and a dress he bought for me laying on the bathroom counter that says "wash up, put on the dress and I'm taking you out for supper" haha it'll never happen but a girl can dream!
Not everyone likes jewelry. I would rather have something that creats a good memory instead. A picnic on the beach, or a weekend trip somewhere.
It used to be that the first jewelry a man would give a lady was an engagement ring.
I think jewelry is a bit difficult, you don't know her taste and it seems to me to smack of wanting to make things more serious. There are a lot of other gifts she would like but I'd stay away from jewelry.