<P> Bohemian glass, chiefly referred to as Bohemia crystal, is glass produced in the regions of Bohemia and Silesia, now parts of the Czech Republic . It has a centuries long history of being internationally recognised for its high quality, craftsmanship, beauty and often innovative designs . Hand - cut, engraved, blown and painted decorative glassware ranging from champagne flutes to enormous chandeliers, ornaments, figurines and other glass items are among the best known Czech exports and immensely popular as tourist souvenirs . The Czech Republic is home to numerous glass studios and schools attended by local and foreign students . </P> <P> Oldest archaeological excavations of glass - making sites date to around 1250 and are located in the Lusatian Mountains of Northern Bohemia . Most notable Czech sites of glass - making throughout the ages are Skalice (German: Langenau), Jablonec nad Nisou, Železný Brod, Poděbrady, Karlovy Vary, Kamenický Šenov (German: Steinschönau) and Nový Bor (German: Haida). Several of these towns have their own glass museums with many items dating since around 1600 . Jablonec nad Nisou in particular is famous for the local tradition of manufacturing glass costume jewellery . Its long history is documented by large collections in the Museum of Glass and Jewellery in Jablonec nad Nisou . </P> <P> The meaning of crystal versus glass changes according to the country . The word "crystal" means, in most of the western world, the presence of lead . In the European Union, labeling of "crystal" products is regulated by Council Directive 69 / 493 / EEC, which defines four categories, depending on the chemical composition and properties of the material . Only glass products containing at least 24% of lead oxide may be referred to as "lead crystal". Products with less lead oxide, or glass products with other metal oxides used in place of lead oxide, must be labeled "crystallin" or "crystal glass". In the United States it is the opposite - glass is defined as "crystal" if it contains only 1% lead . In the Czech Republic, the term "crystal" is used for any exquisite, high quality glass . Leaded crystal means crystal containing more than 24% lead oxide . </P> <P> The presence of lead in crystal softens the glass and makes it more accessible for cutting and engraving . Lead increases the weight of the glass and causes the glass to diffract light . Glass can contain up to 40% lead, if maximum hardness is desired . On the other hand, crystal can contain less than 24% lead if it has a high proportion of barium oxide, which ensures high quality light diffraction . </P>

Who makes the best crystal in the world