Lead Glass is a variety of Glass
in which lead replaces the calcium content of a typical potash glass. This dramatically increases the refractive index and dispersion of the glass making it much more attractive for use in decorative objects, glassware and jewellery.
The technique of adding lead oxide (in quantities of between 10 and 30%) was originally discovered by Englishman George Ravenscroft in 1674. It improved the appearance of the glass, made it easier to melt and manipulate.
True Lead Crystal glassware is rare nowadays because of the potential health risks of lead that it contains. Lead oxide is now replaced by barium oxide, zinc oxide, or potassium oxide. Lead-free crystal has a similar refractive index, but it is lighter and it has less dispersive power.
Glass products that contain 24% or more of lead oxide may be referred to as "Lead Crystal". Products with less lead oxide, or with other metal oxides (which are used instead of lead oxide), may be referred to as "Crystal Glass
Lead Glass is used for decorative objects and cut into beads.