I'm trying to mode my lamp and I have a problem with the light:
This is how it looks when it's off-

and on (sorry about the poor quality, but I AM photographing a lamp after all. still, it is good enough for my purpose...)


I've modeled It's bottom and added an ambient and point lights.
this is it without the lights:

and the renders:



the problem is, as I understand it, is that the light does not effect the faces that are directed away from it, even though the object is partially transparent.
I've got raytracing and shadows(for the point light) on.

Does anyone has an idea for how to make this look more realistic?
Also, How can I make the materials closer to the real thing?