Abstract: A lead-free crystal glass composition includes 58 to 64% by weight of SiO2, 0 to 0.5% by weight of Al2O3, a mixture of alkali oxides and alkaline earth oxides including 13.8 to 18% by weight of a mixture of alkali oxides including K2O and Na2O, and 9 to 15% by weight of a mixture of alkaline earth oxides including BaO and SrO, the ratio of the mole percentage of the mixture of alkali oxides to the mole percentage of the mixture of alkaline earth oxides being between approximately 2 and approximately 3, 6 to 10% by weight of ZnO, 0 to 1.20% by weight of Sb2O3, 0 to 0.5% by weight of SO3, 0 to 6.8% by weight of TiO2 and 0 to 6% by weight of La2O3, and 0 to 10% of colouring agents.

Abstract: The invention concerns a volume of transparent amorphous vitreous material such as crystal or glass whereof one part of the outer surface is coated with successive layers of metal or ceramic particles designed to provide it with a decorative dichroic visual effect when said part is observed through a volume of the transparent material. The succession of layers observes the following scheme: at least one alternation of two transparent layers of metal and/or ceramic particles in contact with the crystal; then a final reflecting opaque layer consisting of metal.

Abstract: The invention concerns a volume of transparent amorphous vitreous material such as crystal or glass whereof one part of the outer surface is coated with successive layers of metal or ceramic particles designed to provide it with a decorative dichroic visual effect when said part is observed through a volume of the transparent material. The succession of layers observes the following scheme: at least one alternation of two transparent layers of metal and/or ceramic particles in contact with the crystal; then a final reflecting opaque layer consisting of metal.