hi...I would like to see it, too...but I think 5 and 7 stone rings are too overwhelming for halos...it most seem to stick to solid bands or matching pave...
Zeghani (Simon G) makes this seven stone. I've actually tried it on and it's gorgeous. Just picture the side stones not being haloed and I think it would look beautiful. I can't get the link to work but the model #ZR494 at Zeghani Jewelry. Good luck!
Here's another seven stone. It could easily handle a small halo around the centre stone without ruining the symmetry. I've seen what you're looking for IRL but finding a pic right now is almost impossible. I think the concept will work beautifully so don't give up. You may have to look at custom or semi custom but it's doable!