The Coquille correcting powders were meant to combat discolouration in the complexion. Yellow combats sallow skin, green covers redness or blotchiness, peach imparts a freshness, etc. It's based on the idea that opposites on the colour wheel will cancel each other out. I like the idea, but find that if not done well, all you get are big splotches of your 'covering' colour. I'm not one for green cheeks, are you?
The only one out of this group that I don't have is the Bleu (blue). If it's anything like Vert, I'm okay not having it. Vert (green) is supposed to ease redness but this is really, really opaque and bright. I'm thinking it'd be a gorgeous eyeshadow. I'd rather use Parfait if I'm going to even out my face. It's a lovely colour though, right?
Lilas (purple) is supposed to help with yellow undertones to liven them up, but this is very, very pale and almost pink. Rose looked peach, and Nectarine was heaven! I use that one a lot. I'm pale with pink undertones and it makes me look more alive. Jaune (yellow) is also good for freshening up sallow or green/olive skin. They do have a bit of sparkle (except for Rose and Vert) so I'd go easy on these. Swatch above taken indoors with flash. Swatch below indoors, natural light, without flash.
There's my comparison chart to show how they appear on the skin. Do you use powder concealers for colour correction? I usually just find a great concealer in a pinkish tone and that does the trick. But I'm glad I have these to experiment with.