I think white sashing would make the blocks stand out. You can see several using Gay's link. You really don't need constrasting cornerstones.

Thanks for all advice. After laying out lots of options and repeatedly ignoring the advice of my usually helpful husband (who wanted a blue-grey) I have decided to go for WOW sashing with co-ordinating corner stones to carry on the ombre theme. So only the last few blocks to finish and then start sashing! The end is in sight...

Black would be nice but it would be a very hard edge. You might want to consider another color...grey? Those beautiful blocks will still pop but it just might be a little softer. Idea #2...navy blue.

White would be my pick - I don't think the quilt needs the "full stop" that a high contrast would deliver.

I think it would look nice with white sashing. Your quilt is going to be beautiful whatever you decide. Please share when you decide and finish.

This is going to finish out to be a very beautiful quilt. I, like others think you would do well with a white sashing in between each block. These are very beautiful block and after all you devoted work on them you may want them to stand on their own. Ultimately it is your decision and any way, you as the artist/ quilter it going to be perfect.

I usually lean toward black for sashings for that Pop, but after checking out the sampler galley Gay so thoughtfully posted I would be hard pressed to pick one. What ever you decide on, your fabrics are beautiful and your finished quilt will be gorgeous!

I have to agree with your choice of white sashing! I can't wait to see the final quilt! It's gorgeous already!

I love your picture where your blocks are laid out on the white background. Your blocks are beautiful and will make a lovely quilt.

What about shadowing them with a medium grey?
I personally think black is going to be a bit stark because there isn't much in the actual blocks.

Watson