It looks very pretty. I remember the first (and only) amethyst my husband bought me. It was an overpriced, maul ring with a hazy, washed out amethyst. lol I still love it because he bought it for me but yours of course is much nicer and blingier. I predict she will love it.
I think it's gorgeous! But keep in mind that a lot of the amethyst out there is highly treated or even synthetic. I think that's fine as long as you paid the right price.
You always have to worry about synthetic amethyst however, but you probably got it for a good price, so I wouldn't worry too much. I have a very similar setting with a cuprian in it. Can't go wrong with a halo!!