No, my sons really are quite dark! They're all base coated midnight blue and highlighted from that. I really prefer to make my Chaos marines as dark and as sinister as possible as they have been wearing the armour for 10,000 years and are the bad guys after all.
The head pieces and weapons are converted from pieces from Scribor (minor cuts and readjustments):
Look for egyptian stuff!
The heads are from grey knight terminators, after filing and filling off the imperial symbols. The combi bolters have the CC weapons cut-off. The book and helmet of the sorceror are from the CSM Lord kit.
The TS crests on the backs are cut to size or greenstuffed larger. And the skull trophy racks have been removed and the holes for them filled in and replaced with smooth armour.