blue-leaning purple. That's so dramatic a difference that I almost wonder if that's a batch issue rather than just the light. (Other bloggers see this as a blue - it's not just me.)
Midnight Cami is a very dark blue shimmer which hangs around on the verge of looking black much of the time. I've seen people call this polish purple-leaning as well, but I can't say that I see it at all. It seems to me like a straight-up blue. This was one of the first Essies I ever owned - I think I bought it from Ulta along with Mesmerize (a brighter blue which should be up soon) and Status Symbol (which is pink), if I'm remembering right.
I was looking at this commentary on Midnight Cami, which talks about staining, and while I don't remember Midnight Cami being a particular culprit there, I was thinking that that may be why I don't wear blues more often, because they're so prone to staining. I was really surprised at how few blues I have relative to purples and greens. And I love blue, as a color.