Patent ID: 8877663

Claim:
Crystal glass having a refractive index higher than 1.53 free of any content of compounds of lead, barium and arsenic, comprising by weight: 55-70% SiO 2 , 0.05-3.5% Li 2 O, 2-15% Na 2 O, more than 3% and less than 5% or more than K 2 O, 15% and less than 19% 5 to 10% CaO, more than 1% and less than 4% or more than ZnO, 7% and less than 8% 0.1-3.5% B 2 O 3 , 0.1-3.5% Al 2 O 3 , 0.1-3.5% TiO 2 , less than 3.5% ZrO 2 , 0.05-1.5% Gd 2 O 3 , 0.05-1% P 2 O 5 0.1-1% Sb 2 O 3 .