Patent ID: 7981823

Claim:
A method for preparing a transparent, colorless lithium-aluminosilicate glass ceramic plate with high-quartz mixed crystals as the prevailing crystal phase, which is provided on one side with an opaque, colored, temperature-stable coating over the entire surface or over the entire surface to a large extent, having a Yellowness Index of less than 10% with a 4 mm thickness, and a variegation of colors of the glass ceramic in the CIELAB color system of C* of less than 5, comprising preparing a composition which preparation includes the addition of 0.01 to 0.4% by weight of Nd 2 O 3 and 0.00001 to 0.004% by weight of CoO based on oxide resulting in a composition as follows in % by weight based on oxide: Li 2 O 3.0-4.5 Na 2 O 0-1.5 K 2 O 0-1.5 ΣNa 2 O + K 2 O 0.2-2.0 MgO 0-2.0 CaO 0-1.5 SrO 0-1.5 BaO 0-2.5 ZnO 0-2.5 B 2 O 3 0-1.0 Al 2 O 3 19-25 SiO 2 55-69 TiO 2 1-3 ZrO 2 1-2.5 SnO 2 >0-0.4 ΣSnO 2 + TiO 2 <3 P 2 O 5 0-3.0 Nd 2 O 3 0.01-0.4 CoO 0.00001-0.004 and one or more chemical refining agents or refining additives in a total content of up to 2.0% by weight, wherein SnO 2 is a refining agent and said refining is a high-temperature refining >1700° C., and wherein As 2 O 3 is excluded, wherein the content of ZrO 2 +0.87 (TiO 2 +SnO 2 ) is 3.65 to 4.3% by weight, to result in said transparent, colorless lithium-aluminosilicate glass ceramic plate.