When the skin gets darker, you have to turn the specular down. That might help. I'm not sure what you're settings are, but if you post them, I'll give some thoughts, if you'd like. :)

You also need a morph that looks like a dark-skinned person. From a psychological standpoint, that would help us see what's right/wrong with the skin. It's funny how something as simple as face shape can make it hard to discern other things...at least for me. :)

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