In artistic glasswork this is the name for clear glass whose quality depends mainly on the purity of the raw materials used to make it. Cristallo must contain the least possible quantity of coloring oxides. To remove the oxides, decoloring substances can be used during the melting process to neutralize their effect. Murano cristallo is distinguished from lead crystal and Bohemian crystal by a longer cooling time, which allows more working time for the molten glass. This is caused by the significant presence of soda and calcium oxides in the molten glass mixture.