Abstract: This invention relates to a crystal glass having a refractive index higher than 1.53 and a high mechanical strength, free of any content of compounds of lead, barium and arsenic and guaranteeing maximum safety for health, which consists in that it comprises by weight: 55-70% SiO2, 0.05-3.5% Li2O, 2-15% Na2O, more than 3% and less than 5% or more than 15% and less than 19% K2O, 5 to 10% CaO, more than 1% and less than 4% or more than 7% and less than 8% ZnO, 0.1-3.5% B2O3, 0.1-3.5% Al2O3, 0.1-3.5% TiO2, less than 3.5% ZrO2, 0.05-1.5% Gd2O,3 0.05-1% P2O5, 0.

Abstract: High-lead content crystal glass shows with advantage the refraction index higher than 1.58, high light transmission, increased mechanical solidity and chemical resistance is suitable, especially, for the production and refinement of glass jewellery products, decorative and utility objects, including chandelier trimmings and semi-finished products. This glass contains, presented in % wt., 48 to 53% of silica SiO2, 30 to 33% of lead monoxide PbO, 10 to 13% of the sum of potassium oxide and sodium oxide K2O+Na2O, 1 to 3% of calcium oxide CaO, 0.5 to 1% of zinc oxide ZnO, 0.5 to 1% of boron trioxide B2O3, less than 0.3 % of barium monoxide BaO, less than 0.3% of aluminium oxide AI2O3, 0.2 to 0.5% of antimony trioxide Sb2O3, 0.007 to 0.01% of oxides of iron.