The lighted slabs are alabaster stone. The wall they are mounted into is about 24" in front of another wall, therefore there is quite a large space inside the wall for lighting. As I recall there are flood lights in the wall cavity, mounted at the bottom shining up, and then the lower side panels are hinged to access the lighting for maintenance.

Another method I have used to light glass-wall features is to use either fluorescent lights or LED's in longer tubes or strips. With that method you need to have a generous amount of depth behind the art work so that you minimize "hot spots". Remember that all installations need to accommodate light fixture maintenance and bulb access along with heat removal vents.

Where did you find the alabaster slabs, I am looking for a client and having a hard time finding...?