Make the inside transparent too.
I figured out the ambient occlusion. It's a less noticeable effect here but it looks nice.
The glass looks like it's mesh is turned inside out, which is the method some games use to have an outline effect
-snip-
How can I glass correctly?
Don't use transparent glass texture. The transparent textures become solid after the item re-spawns on a brick.
"My vision is augmented." This is JC Denton from Deus Ex in case you don't know