From history we know that the idea of creating crystal belongs to the British: they were the first to add lead oxides to the charge material, and as a result got glass with unusual “voice”, transparency and sparkling faces. Classical crystal contains 24% of lead oxide, but there are products with a higher content of up to 30%.
The percentage of lead oxide in the crystal affects its "vocal" abilities, transparency, durability, weight, gloss and other properties.
In addition to lead crystal, there is also barium crystal, in the production of which barium is added in the glass instead of lead. Bohemian crystal is also very widely known in the world. In its creation, instead of lead and barium, potassium-calcium glass is used.
According to the European Standard, glass products containing less than 4% of lead oxide are referred to as "glass". Glass products with a lead content of more than 10% are "crystal glass", and glass products with a lead content of more than 30% are called "crystal with a high content of lead oxide."