Shaped glass or glass ceramic article

A shaped article obtained from a disk-shaped starting glass ceramic article having at least one deformation of the depth T, in which: - T> (AdρBg) / (γl) in which A = surface of the starting glass to be lowered in m ρ = glass density in kg / m g = acceleration due to gravity in m / s γ = surface tension of the starting glass in the molten state in N / m, d = thickness of the starting glass in m, B = width of the deformation in m, l = amount of deformation in m, wherein the surface of the molded glass article after molding has no impurity greater than 1 .mu.m, in particular of greater than 0.1 microns.