Glass Manufacturing)..Crystal Glass )

Crystal glass (also just named Crystal) is a form of glass with a high degree of transparency that usually consists of a high proportion of lead oxide. For this reason it also called “lead crystal glass”.

It is traditionally hand-blown. Crystal is ?brilliant? because the increased refractive index causes noticeably more ?sparkles?. Generally, the crystal glass makers add 24% PbO into the molten glass during production to get the best final product.  In this formulation the specific gravity, the refractive index and the hardness of crystal glass will be superior to those of normal glass. In order to get the best crystal glass art, the makers should purify the melting glass liquid, which contains 24% PbO, and hand-blow it. After grinding and polishing, as well as careful workmanship on the creation, brilliant works of art come into being.  How to distinguish glass and crystal glass? It is a common puzzle for people who are not familiar with them. You can judge it in the following ways.  Sound  The sound will be different if you tap on a glass or crystal glass vessel. You will hear the silvery reverberation from a crystal glass vessel. For a normal glass vessel, the sound is duller and without reverberation.  Weight  For products of the same size, the crystal glass one is heavier than the one made of normal glass.  Refractive index  The refractive index for crystal glass is stronger than that of glass when under the same light conditions. Crystal glass can emit colourful rays but the normal glass will not.  article source http://www.glassonweb.com