Glass effects with opaque materials

Ok. I need to model a 2 layer object. The bottom layer must be an opaque layer that does not allow any light through. Easy enough.

The top layer is a glass like material that lets all light pass through with near zero shadow. Easy enough.

The problem is I do not know how two materials act when they are literally touching, and connected, to each other. Imagine a pane of glass face-glued, sandwhiched, onto another pane of glass, but one of the panes is opaque. How would the light in ray tracing work with this kind of connection boundary?

Can I leave a tiny space between the layers, acting like pure air, and get the same result?

Any help would be greatly appreciated.

in wiki page on light and transparency there is a variable ( depth) defining the number
of reflection inside a glass
if not enough then the bottom will appear opaque

so check out th wiki page for this effect in mirror panel

this should work well or may be try with yafaray renderer