Potomax Ginko Bead - Antique Brass. You’ll love the look and feel of durable metal beads in your jewelry designs. Each bead is cast in Zamak zinc alloy, then plated in antique brass. These alternative metal Ginko beads can be used in place of many different Czech glass multi-hole beads. Let your imagination soar as you create with these stylish metals. Potomax Ginko beads measure 7.5mm, have 2 holes and come in a pack of 50.