glass thickness

This might be a bit more tricky than I had hoped, but we'll see...

I'm modelling a surgical instrument, the main body of which is shaped
somewhat like a rectangular vase with a hole in the bottom. The body
of the actual instrument is clear plastic with a purple tint. The
trick is-- the only parts that really show as purple are the areas
where the viewer is looking at the thickness of the body (the edges)
the rest of the body remains transparent.

My first question is, how do I create the illusion of glass/plastic
with thickness?... (I've modeled the body with an inside and outside
edge, but it doesn't look right)

Secondly, are there any suggestions on how to get the translucent
purple to show up on the edges?

Thanks... let me know if I need to clarify anything.