Crystal or glass? What is the difference between crystal and glass? The difference between glass and crystal is determined by the accepted jurisdical regulations (related to segmentation of glass and crystal into different cathegories) of each country. For most countries the word crystal means there is Lead present in it.
According to the laws of the European Community, glassware containing less than 4 % PbO2 is defined as "glass", glassware containing more that 10% Lead is "Crystal" and glassware with more than 30% Lead is called "High Lead Crystal".
On the other hand, in USA glassware with as little as 1 % is qualified as "Crystal". In other countries, it is a question of the meaning of the term „Crystal“, which may be used for any refined, high quality clear glass. Leaded Crystal in this case is understood to contain more than 24% of PbO2. The presence of Lead softens the glass, thus it makes it more vulnerable to cutting and craving. Lead adds volume to glass and enables glass to refract light passing through it into the colours of the rainbow. Another variation is Crystal containing less than the standard 24 % Lead, nevertheless it has a higher percentage of PbO2, which secures the sufficient quality of refraction of light.