I think the colors are very carefully chosen for the shoot, and then I think there is some digital processing going on, probably through the use of adjustment layers. I see quite a variety on the site, so specific examples may help. Also, some of the models have that new-wave (I call it) luminosity to their skin tones---I think another photoshop trick, one I haven't figured out yet. Most of the shots are likely done with a very large light source....maybe a daylight studio, or large diffusers or somethig like a large octodome with a strobe. I will reiterate that everything seems to have been cleaned up and toned, at least to some extent, digitally.