Abstract: A method for preparing a phosphor including heating at its reaction temperature in a covered container a mixture of zinc sulfide, an activator quantity of copper as a compound thereof, an activator quantity of aluminum as a compound thereof, an activator quantity of gold as a compound thereof, a minor proportion of elemental selenium, a minor proportion of elemental sulfur and a minor proportion of carbon. The reaction mixture is heated in the container and the product is then cooled. After cooling, whatever carbon remains is removed as by screening.