Hi nruddock,

I think I'll stick with my own method. It seems to work, it doesn't involve any "exotic functions" or special lighting and it's quick'n'easy to do.

It'll be good enough for what I want to do, and I'm happy with it :-)
It does what I want it to: Doesn't reflect the green sphere (not very much, anyway - I might want to increase that a little in the glass front) and I get the semi-infinite reflections for the enclosed objects. ("Semi" infinite 'cos I only upped the no. reflections to about 15 - that was enough for this simple test.)

I only posted in case anyone else was wondering "how to". If anyone is and can't understand my somewhat terse explanation of what I've done I'll be happy to explain in better detail.

Cheers,
Diolma