Karen,
I love the colors you are working with and this is going to be beautiful when you are finished. Reminds me of appatite jewels or a london blue topaz.
First I would finish off the design along the edges to finish the little block like what in in the center of your quilt. Eliminating the dark sections.
Then the white as a border, then perhaps a strip of tiny squares like the center block. If you think of each little block as a mini of the design, that would be perfect. It would be a design block a white and design and so on like a chain of daisys. Just a chain of them to go all around would be sweet. Then a white border. It would give some intrest to the borders and make it larger.
Then go for your dark borders.