Lead or crystal glass contains 18-40% lead (II) oxide (PbO) by weight. Lead crystal glass is desirable for its decorative appearance, having a higher refractive index, dispersion, and density than other types of glass. Laser processing of lead crystal can be accomplished with a 10.6 or 9.3 micron CO₂ laser without a discernible difference in processing quality. Laser marking of lead crystal glass produces a smooth uniform mark with little contrast. Alternatively, dithering can be used to create a pattern of surface microfractures, resulting in a uniform mark that is frosted in appearance. Laser engraving of lead crystal glass produces a smooth mark with depth and a melted appearance.