Instead of adding another datk blue border, I would stop and do the binding in dark blue for a nice little frame.

If you go with white it will open it up again. I would close it with the blue. It is so pretty! Or go with what Sewmary says.

Dark blue would be best. However, I think an even thinner border of dark blue would be best so it doesn't distract from the exquisite softness of your quilt. Such a beautiful quilt!

Ooops, I didn't see Sewmary's advise on the binding being dark blue. That would give you your thin line to finish it off nicely.

Depends on what you want the quilt to be. If you want to continue with the softness of it the dark blue that wide will make a bolder statement. The lighter colors would keep it soft. Is there a reason you don't want to piece the next round? Maybe a thin white and repeat the blocks and then do the dark blue binding.

I too like the dark blue. It is so pretty!

I would go with the dark blue. By the way this is looking great.