@thomthom said:

Emissive materials should not be used as primary light source. Use omni or rectangular lights as primary.

Thanks ThomThom !

It helps me too, because I tried this http://sketchupvrayresources.blogspot.ca/2011/07/trick-removing-splotches-in-vray.html

But it's still the same!

Now with a rectangular light it's really better.

Hello!

I'm Curtis and I use Sketchup for a while. (Maybe 5-6 years)

Now I have VRAY and it's so realistic!
But this forum will certainly help me ^^ Sometimes I have difficulties even when I saw all the good answers.