If I understand you right, you're going for the engraved look? Try playing with the lights, they have a HUGE impact on Sketch renders. You can use the Cartoon-with-lines display mode to determine the shadows before sketching.

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You just can't put the words "Poserites" and "happy" in the same sentence - didn't you know that? LaurieA
  Using Poser since 2002. Currently at Version 11.1 - Win 10.