Believe Ivo & Co right on this one (can't argue with an expert) but for future reference you can normally tell not top quality gemstone beads by examining the strung necklace and just looking for non-alignment.
Sometimes, the holes in mineral beads are drilled only part through, bead is turned and same done from other end, hopefully meeting in middle and drilling not necessarily done truly on the central pivot/axis. Of course, this would be much easier to identify with regular shapes such as spheres, and you can sometimes see that they don't all hang absolutely true to line. However, in your case, the facets would distract and make this visual type appraisal much harder.