Good source for a fine stackable diamond band?

[sapphiredream]

My husband and I decided I should look for an anniversary band. I would like to find something narrow/thin that I would stack onto my current wedding which is also a thin (2 mms) white gold band with half channel-set diamonds.

I know such bands are everywhere now but I need to find a vendor with fine craftsmanship and high grade diamonds.
There's nothing more frustrating than to purchase a piece of jewelry with diamonds only to realize the diamonds do not sparkle at the maximum they COULD sparkle.

Could anyone recommend such a vendor? The band itself would have to stand out through fine work and high grade material - otherwise it's just a thin band, nothing special.
I looked at Blue Nile and while some bands look like a possibility in the picture, I have no information about their diamond quality/grade.

Thank you for any vendor recommendations!