Vray Materials

http://viscorbel.com/vray-materials-theory/

http://forums.cgarchitect.com/74801-fresnel-ior.html

http://forum.vrayforc4d.com/index.php?threads/7571/

Using Selection Sets with Vray Materials

To have an identical material on several selection sets on one object:

Make one copy of the material per selection. So if you want to use the same material on 3 selections you need 3 copies of this material. If done this way, the same material can be applied to selection sets with different uvw projections. 

[Source: Vray Forums]