Aye, Madmax might be right, but lack of ray-septh would produce null-reflections which are black, not white... Is the etching geometry-based, or material based? Are you using booleans to actually carve the diamond? If so, try Madmax's advice... If it's a texture, try using the source image as a lattice and carving into the glass, it might produce better results. Thus, you could use the negative to "paint" the etch material into the glass....? Ideas...