Crystal is a material of glass that consists of a certain amount of Lead (II) oxide (PbO). In the 18th century, the English discovered that the addition of lead oxide to glass gave a clear difference in the clarity and brilliance.
The lead makes it easier to process the glass. The lead also gives weight to the glass and the light breaks down rays, so that the light that shines through it is shattered in the colors of the rainbow.
European Community rules state that glassware with less than 4% lead oxide is called ‘glass’, with more than 10% lead is called ‘crystal’ and more than 30% is ‘high lead crystal’.
Crystal consists of quartz, which is a mineral that is made up of a compound of silicon and oxygen.