Case with double centerpiece catherine wheel. The double crystal technique again shines in this remarkable centerpiece. Catherine's wheel displays an outer layer in colored glass and an inner layer in clear crystal. The cut of the first layer reveals the clear crystal, creating an unusual contrast between the two strata. Evoking a wind vane, this piece is inspired by a type of circular firework: when lit, an angled rocket mounted with a pin through its center rotates quickly, emitting a display of sparks and colorful flames.