Thank you NHBabs. I saw Solina at Brushwood. Earlier this season A Way To Garden did an interview with Dan Long at Brushwood, where he said it was a pale blue that reminded him of Perle d'Azur. The photo there does not quite strike me as blue, though -- it looks more like light eggplant purple (I actually like the color).

Clematis on the Web describes Solina as lilac and Emilia Plater as blue-violet. All the photos I see of Solina have 6 petals while most of EP have only 4, with a bit of a darker stripe down the center of each. I can't do a direct link to CotW's pages for individual plants, but here is the CotW search page. Just put in the name (or part of it - the software doesn't like spaces, so only use one word of EP) and leave the rest blank, hit the search button, and you will get a link to a list of information of the plant.

Thanks again -- Solina looks far more pinkish at CotW than I imagined she did. Indeed they say "initially with pink tinge" so I guess those photos mostly do her justice. So for now she is probably out -- blues are really hard!

Remember that clematis colors are really difficult to photograph accurately and also that the actual color will vary some with age, sun exposure and lighting at a given time for many of them. Yesterday I tried taking photos of a true purple with an overcast sky and it came out with red highlights.

The best way to know is to see it in person. Second best is to ask someone who has seen it as you are doing here, though it seems like no one here has. You could ask Brushwood to compare the two.

I asked on a clematis Facebook group that has a lot of experienced growers. Here is the one response I got so far:

I have both. Emilia is bluer with smaller squarer flowers. Both are good and last a long time but I prefer Solina. Both are vigorous.

Thank you so much! Very helpful. Emilia may look even smaller partly because, as you said, they seem to be with mostly four petals (some photos I've seen show five in the mix, but most seem to come with four -- seems four or five), while Solina comes with six.