Is this going to be a right hand ring for her? If so, I think a three stone would be great. The one carat stone in the center and whatever sizes on the side. I think a three stone is the perfect combo between simple..yet a little fancier. Since she's so attached to her original ring ( I don't blame her at all) I hope he's not getting this ring to "replace" it because she may not wear it on that finger....just a thought. A three stone makes a great right hand ring too! Good luck! I'm sure whatever you pick will be great and she will love it!