Effect pigments

An effect pigment based on an Al2O3 flake which comprises:

• an Al2O3 flake coated with one or more layers of a metal oxide and/or a metal oxide mixture:
• wherein the ratio of the amount by weight of Al2O3 of the Al2O3 flake to the amount by weight of the metal oxide(s) of the coating layer(s) is in the range of from 27:73 to 83:17 based on the total weight of the effect pigment;
• wherein the Al2O3 flake has a standard deviation of thickness distribution of less than 80;
• and
• wherein the effect pigment contains on the surface a protective layer that is an organic compound, wherein the organic compound is a coupling agent selected from the group consisting of organosilanes, organoaluminates, organotitanates and zirconates, wherein the protective layer contains at least one rare earth metal oxide or hydroxide in an amount of 0.2-2 wt % based on the total weight of the effect pigment, 0.2-2 wt. % of SiO2, 0.2-4 wt. % of Al2O3 and/or ZrO2 and 1-10 wt. % of the organic compound;
• and
• wherein the effect pigment contains only one protective layer and/or the thickness of the protective layer is from 1-5 nm.