So FI and I kind of forgot that we needed to get wedding rings until this weekend. Anyway, I decided awhile ago that I wanted an amethyst and diamond band. Or a thin diamond band with a bottom amethyst band. I have looked everywhere including esty and I can't find what I'm looking for. I have never had anything made by a jeweler before so I have no idea what it would cost - so I'm working on finding something instore or online. Bluenile.com was no help. Here is what I am looking for:
This is the ring we currently intend on getting.

I want something like this but with princess cut diamonds.

My ring is really strange and while I have round cut pave diamonds on both side settings my center stone is princess cut and the ring looks better with a princess cut band. If I can't find an alternating diamond/amethyst setting, I would like a top band like this:

And a bottom band like this but with princess cut stones and a lighter purple if possible:

I would prefer white gold just to match my e-ring. Any ideas? I have looked and looked but I can't seem to find what I'm looking for.