The size of these square coin pearl beads is 10-12mm plus nodelle. Silvery white color. Thick nacre & beautiful luster. You need to see these rare coin pearl beauties to believe it! Freshwater coin pearl beads are created when a small flat disc shaped shell, instead of a round 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 a fabulous flat disc shape pearl. Our freshwater coin pearl beads are picked by their luster and size.