Im an engineer by trade... talking from experience, the "burnt chrome" effect looks in fact like it is nickel. Chrome does not react so extremely as that when it is heated. Chrome is affected similarly, but it is far duller. I would say that all of the "burnt" covers in the gallery are in fact nickel. The Camo effect looks like a chemical etching onto a nickel cover (probably Haematite or Tourmaline ferrous patanating fluid) so the two would effectively cancel each other out if both applied.