Faceted Oval Crystal Prism - These Faceted Oval Prisms from the United States have a clear "window" center but are also very refractive and are strung with a filament for hanging. Crystal is a form of glass that has lead oxide (Pbo) in its chemical composition. These crystal prisms are precision cut and polished just like diamonds to achieve the maximum amount of sparkle and luster.
The purpose of lead oxide is to increase the density of glass which, in turn, increases the refractive properties. When it is cut and polished it creates more sparkle than regular glass. The higher percentage of lead oxide in the composition of crystal, the more colors are reflected from it.