6mm Moonstone smooth round beads are transparent man-made that diffracts reflected light creating a cloudlike floating blue within it called schiller. Moonstone is a great jewelry stone as it can pick up colors from your clothing (try moonstone against black).
The hole size is 0.9mm - big enough for a 20 AWG wire but too small for an 18 AWG wire.
These beads are man-made and as such are smooth and uniform in color.
Strands are sold as temporarily strung. Strands are approximately 16" and can vary +/- 0.5".