Magnetic pigments

A magnetic pigment, comprising

• a transparent flaky homogeneous substrate having two parallel major surfaces wherein said substrate is a synthetically produced material of Al2O3, of Al2O3 containing up to 5% by weight TiO2, of SiO2, of SiO2 containing up to 20% by weight silicon hydroxide, of glass or of a borosilicate
• and
• a coating comprising a layered structure, said layered structure consisting of a first layer comprising hematite and/or goethite having a thickness, and of a second layer comprising magnetite, the second layer having a thickness and being located on the first layer, in this sequence, at least on the two major surfaces of the substrate, wherein the thickness of the second layer of magnetite is larger than the thickness of the first layer of hematite and/or goethite
• and
• wherein the magnetic pigments further comprise one or more dielectric layers on top of the magnetite layer wherein said dielectric layer comprises a silicon oxide hydrate layer being located directly on the magnetite layer and a high refractive index layer on the silicon oxide hydrate layer.