Process for the production of purple pigments

A process for the production of a purple pigment based on a fireable support material selected from the group consisting of a glass flux, other oxide or silicate material and mixtures thereof coated with colloidal gold, comprising bringing a finely powdered support material into intimate contact with at least one gold compound, wherein the weight ratio of support materials to gold in the gold compounds is between 10:1 and 2000:1, characterized in that

• (i.sub.1) the support material and the gold compound or compounds are intimately mixed and/or ground in dry form or
• (i.sub.2) the support material is brought into contact with an aqueous solution or suspension of the gold compound or compounds in the absence of a reducing agent and without adding a precipitation agent for converting the water-soluble gold compound or compounds to water-insoluble compounds and
• (ii) the resultant mixture is thermally treated at a temperature above the decomposition temperature of the gold compound or compounds and below the sintering temperature of the support material until the gold compound or compounds are converted into colloidal gold.