Q: does you mind picture the glass slipper as clear glass?

A: Yes.

Q: sole and heel of the shoe are a different material?

A: Yes. Dark, opaque.

In my mind I picture it as a simple high heel shoe. Plain glass, not cut glass, not tinted or etched, with a shiny black heel and sole. In Poser that might be hard to represent. Perhaps a lightly etched pattern would work better.