4mm Umber Druk Czech Glass Beads. The area now known as the Czech Republic has been a leader in the glass industry since the Middle Ages. Factories in the Czech Republic continue to produce the highest-quality and most innovative glass beads. Czech Glass can be easily distinguished from lower quality glass produced elsewhere. This difference is most easily observed in the consistency, quality and variety of color and finish, as well as the consistency and quality of cut and shape. Round, unfaceted Czech Glass beads may also be known as "druk" beads. Sold 100 beads per strand. Sold by the strand.