It is certainly not wilt, so no worries there!! Actually the plant looks extremely healthy......do you know the cultivar name? It looks a lot like Multi Blue that has not yet fully opened and spread that interior boss of tepals.

As to the color......if it is Multi Blue, it will never be a strong purple color. At best this is a lavender blue. I am not aware of any other clem with a deep purple coloring with this same sort of bloom formation. And growing conditions can affect the intensity of flower color - the stronger the sunlight the vine receives, the more washed out the color will be, specially with blues, pinks and striped or barred forms. That is one of the reasons it is difficult to accurately ID a specific cultivar - the flower color can be extremely variable based on sun exposure, climate and growing conditions.

I don't think this is multi blue. I just compared the buds on my Multi blue to the pictures above and they are not similar. Can the OP please post a picture once the buds have completely opened up.

It's supposed to be a diamantine clematis.

What would you do if this was yours? Move to a shadier spot? I thought clems liked sun. This gets sun until maybe 2?

Probably it needs to be fertilized, its leaves are noticeably yellowish.

What clematis like is tops in the sun but roots in the shade. So yours might do better if there was a box right in front of it, instead of only at the sides. Although the sun hitting the root zone during part of the day certainly hasn't killed it so far.

Photos for anyone wanting to see what is presumably typical for this particular variety (notice that many shown on page below are not as dark as in the picture that came with the plant):

http://www.bing.com/images/search?q=evipo039&qpvt=evipo039&FORM=IGRE

If you look at the breeder's website, the flower color they show is very similar to yours. A lavender blue - not a purple. However your flowers are not yet developing in the same manner. I see no sign of obvious doubling. But that may just be a factor of time/age.....both of the plant and of the individual flowers :-)

ETA: the notion about "roots in the shade " is a bit of a clematis growing myth :-) The roots do not require shading - what they want is a cool and consistently moist root run. And while that can certainly be achieved with planting the roots in the shade, it can also be accomplished with just a good layer of mulch or some other lower growing plant at the base. And the foliage does not look the slightest bit yellow or off color to me......looks like very normal, healthy clematis foliage!!

That actually sounds like a good spot for it and it does look happy and healthy. I think the slightly lighter green leaves are just newly opening, not indicative of any issues. What I would do is plant a second clematis with deep purple flowers. I think that the contrast of form and color will make the two shades of purple both look better. A couple with rich purple to check out Blue Bird AKA Edomurasaki and Daniel Deronda, both of which I have seen sold in American nurseries.

”I’m close to tearing these out.” I would wait until the flowers fully open to see if the color is more appealing then, and also see how it looks with deeper purple plants. If ultimately you decide not to keep it, please rehome it rather than literally tearing it out. I am sure that it is a plant that other gardeners would welcome since you have grown it so well.

I have 'Diamantina' and she looks just like yours. There is absolutely nothing wrong with your Clematis.

I happened to be at the Rogerson Clematis Collection today and here is 'Diamantina'

Emily,

There is nothing wrong with your plant. I thought that I got the wrong plant too when my bloomed. I was expecting a deep purple like those on websites. However, searched on youtube from other people who have this varieties, I realize that I get the right one. My looks exactly like buyorsell888.

Emily,

If you like deep purple, then try Belle of Taranaki.

Some doubles aren’t as likely to be as double when grown in cold areas where the vines die back more. I don’t know if it is the case with Diamontina. But if you look carefully at BorS’s photo, two near the middle are more single like yours, while the rest are more doubled.

Somehow the tags got printed wrong and photos with the wrong color are all over the internet likely all from the same source. Raymond Evison is the breeder and his website shows the lighter color. I went and looked at my own and they are fully open now but all the outer tepals have dropped and they are very much on their way out.
Raymond Evison Clematis Diamantina