The earliest known Chinese glass beads were crafted during the Western Zhou period, from the ninth to eighth centuries B.C. They were probably the outcome of attempts to imitate jade, an important and precious stone for the Chinese. Glass proved to be a good substitute and easier to work as a material. Makers of glass beads became more proficient and produced complex designs during the Zhou dynasty and in the Warring States period (475–221 B.C.). Near the end of the Zhou dynasty, unique Chinese eye beads were fashioned. These beads differed from other, contemporaneous beads both in style and in the materials used in their construction. Chinese glass of this period contains a significant amount of lead and barium, resulting in a heavier bead. The Chinese were also making composite beads, which consisted of glass layered on a fritted core that was made on a base core of terra cotta. They developed a “revolving eye” form, in which the pupil is placed off-center; in addition, eyes are clustered into small rosettes (e.g., 51.6.552 and 51.6.572). This example of a horned eye bead was made during the height of Chinese eye-bead production. The stratified eyes protrude from the surface, revolving around the circumference of the bead, along with smaller rosette eye clusters that are also raised above the surface. This and other Chinese eye beads of this period are extremely complex in design. The eyes used are more decorative, and they do not convey a protective quality, as in other eye beads made in Western Asia and Egypt. The high quality of glass beadmaking exemplified here disappeared at the end of the Zhou dynasty, and Chinese glass beads reverted to simpler forms in the ensuing centuries.