Hi,

After some research it seems I need to modify the subsurface scattering  to get this effect.
Here is a great link to the theory. There is a section on wet materials.

http://graphics.ucsd.edu/~henrik/images/subsurf.html

Quite tricky indeed! I don't know how to apply this even in Carrera for example where they have SSS.  Maybe I can try your trick in Bryce plus simply darkening the material in some places.

l3la