If I am not mistaken, Opensim is using OpenGL. You are never going to achieve that 'perfect' realism but you can utilize an "on object" approach. You'll need a matching skin set with bump and shine maps, most avatars I have seen in the Opensim do not appear to have those maps applied to them. There are plenty of online map generators you can try to make bump and shine maps for the skin.
EDIT: I had to look at your sample image a couple of times... it appears you may have done what I just described. WELL DONE!
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