I'm really enjoying working with the viking knit weave - I set an odd-shaped stone with copper wire the other day. It looks round, but the surface is actually wavy which made setting it interesting to weave around! I'm not sure what type of rock it is, but it's very smooth and mostly a mauve color, undyed (natural). I asked when I bought it, but the lady wasn't sure.
The wire frame (heavy gauge wire) looks out-of-round because of the wavy surface of the stone. It was actually a large focal bead, but I'm liking it better treated as a cabochon.... I haven't yet decided if I'll make a chain for it or not. Currently it is being used as a sample for my students' perusal.