The average size of these beautiful freshwater square coin pearl beads is 20 x24mm. 8mm avg. thickness. Looking for a freshwater coin pearl? These are the ones! Beautiful, lustrous, square coin pearls. Each coin pearl bead is natural in shape, no two exactly alike. These freshwater coin pearls are the bomb! Seriously, great value for this sort of quality coin pearl. Freshwater coin pearl beads are created when a small flat square shaped shell, instead of a square bead, is inserted into the oyster or more commonly these days, mussel. Most of these pearls are farmed in rivers, lakes or streams. The result is a fabulous flat square shaped pearl. Our freshwater coin pearl beads are hand picked by their luster and size.