Hi all! Four stones deep into faceting and really enjoying it. This is despite paying too much for a machine that's very challenging to say the least. Only cut Quartz and Topaz(2nd from left) so far but want to cut some Tourmaline next. Just hoping someone can help me out with understanding how to choose which designs will work. Do I use one that's designed for a higher or lower RI. For example can I cut Tourmaline with the same patterns that I've used with the above stones or do I have to look for ones over the 1.6 RI? Hope this makes sense and thanks in advance for your help.