Potomac Crystal Round Beads 4mm - Tanzanite. Exclusive, high quality Potomac crystal round beads are faceted to bring beautiful sparkle to your next project. Use these brilliant crystals for any designs that call for Swarovski 5000 shape. Potomac Crystal Round Beads measure 4mm and come in a pack of approximately 100. *Bead sizes and counts are approximations, based on expected quantities and actual counts on samples selected at random from inventory to verify bead sizes and quantities. The number of beads you receive may vary from the approximate quantity indicated, but it should be within range.