I have a 1.9 round E color, excellent cut, S1 (eye clean) that I got from a jeweler after much negotiating for around 10k. It is really beautiful and looks well sized on my size 4 fingers...however, I really love cushions and radiants!! I had my eye set on them from the start but somehow talked myself out. I kinda regret it now. We bought the ring two years ago and am wondering if it would be possible to exchange it for a radiant or cushion? If we were willing to put another 5k down, what could I get? I''m assuming more since round brilliant is a more expensive cut per carat than the others? We have a good relationship with the jeweler so I think she''d let us exchange but I''m wondering how much more in size I could get with a cushion or radiant. Any thoughts or suggestions?