Everyone gave you really good advice. The last ring you showed would be a very beautiful style. I would NOT pick a wedding band now - let her do that or do it together.
You can also always get a temporary setting, like a solitaire from stuller, to mount the diamond so she can wear it right away and tell her you would like to design a dream ring with her. Would she appreciate that?
Yes, I'm very grateful for everyone's input.
The diamond is going into a basic four prong basket solitaire setting like I've seen in many of her searches. I will pitch the idea of dressing it up with a collection of different wedding bands.
If she wants to redesign, she can, but I was always going to offer this, even with the halo. Nothing's permanent. I'm guessing these boards have seen many posts about fixing botched designs after the proposal. Call it one less now, ha ha
I do pay 5% less import tax for a loose diamond, but I feel like I have to give the poor jeweler some business after he spent the weekend putting sapphires into a halo CAD because the client doesn't know anything about style.