What is the difference between crystal and glass properly?
The composition of glass is SiO2. Crystal is the glass with high content of Pb inside, i.e. 24% PbO is added into the glass. The internation standard of PbO content is 24%, with this percentage the physical and chemical performance is the best. The specific gravity reaches 3.17g/cm3 (it is more heavy than glass). The refractive index reaches up to 1.545 (it can transmiss the spectrum color) but it is about 1.2 for glass. The high transmission percentage can reaches 90%, also crystal has high hardness and wearable.
