What is lead crystal glass made of?

The inclusion of at least 24% lead oxide in the composition is required by law for crystal to be called full lead crystal. The lead lends brilliance and weight to the product. Crystal without lead is still crystal, i.e. clear glass, however, it is more commonly perceived as &quotglass". The lead also make the crystal softer and more conducive to cutting. This is why the lead crystal is cut and for the most part, the unleaded crystal is not cut.