Bought as NOID last year, opened two buds yesterday:

Just guessing:
Could it be a Clematis Fleuri?

Or a Clematis Amethyst Beauty? The description for this one says 'slightly wavy petals'.

I was looking at a site called Klehm's Song Sparrow, Farm and Nursery, Fine Plants - they are in Wisconsin.

Sorry, the color on these didn't come out too well. They're a really deep blue violet color.

Could be the popular Clematis 'The President'
Keep taking additional photos because the first few blooms may not truly represent the bloom yet. The pinky-white filaments and red tipped anthers seem to match though.

Would it help to make some adjustments to the color, maybe the color balance?, in the camera so we can see an accurate bloom color? I don't know how to do this but posting on the photography thread might get an answer.