The present invention relates to interference pigments based on multicoated flake-form substrates which have on the surface of the substrate a layer sequence comprising (A0) optionally a high-refractive-index coating consisting of a layer of TiO.sub.2, (A) a high-refractive-index coating consisting of a mixture of TiO.sub.2 and Fe.sub.2O.sub.3, which may optionally be doped with one or more further oxides, (B) a high-refractive-index layer consisting of SnO.sub.2, (C) a high-refractive-index coating which absorbs in the visible wavelength region, and optionally (D) an outer protective layer, and to the use thereof, in particular in paints, coatings, industrial coatings, automobile paints, automotive refinish paints, coil coating, powder coatings, printing inks, plastics, pigment pastes, pigment preparations and in dry preparations, such as, for example, granules.

Disclosed herein is an effect pigment having a layer stack which comprises a highly reflective metallic flake having a first major interface and opposed to this first interface a second major interface, and at least one side surface and directly adjacent on one or of both of these major interfaces a layer of a semiconducting material having an average atomic composition of: a) Si.sub.(1-x)Sn.sub.x, wherein 0<x<0.90 or b) Ge.sub.(1-y)Sn.sub.y, wherein 0<y0.80 or c) Si.sub.(1-m-n)Ge.sub.mSn.sub.n, wherein 0<m<1.00, 0<n<1.00 and with the proviso that m+n<1.00.

The present invention relates to a process for preparing a coloured effect pigment, comprising the steps of (a) preparing in an aqueous coating medium at least one layer of a hydroxyl-containing metal oxide on a substrate, thereby obtaining in the aqueous coating medium a first coloured pigment material CPM1 comprising the substrate coated with the hydroxyl-containing metal oxide, wherein the substrate is made of aluminium or aluminium alloy which optionally comprises at least one passivating layer, and wherein the hydroxyl-containing metal oxide is a hydroxyl-containing iron oxide or a hydroxyl-containing titanium oxide or a mixture thereof, (b) providing the first coloured pigment material CPM1 in a liquid post-treatment medium comprising one or more high boiling organic liquids, and (c) heating the liquid post-treatment medium to a temperature of at least 90 C. so as to convert the first coloured pigment material CPM1 to a second coloured pigment material CPM2.

Disclosed herein is a flaky diffractive effect pigment having a diffractive structure and comprising a flake of a highly reflective material having a first major interface and opposed to this first interface a second major interface, and at least one side surface and directly adjacent on one or of both of these major interfaces a layer of a semiconducting material having a bandgap of 0.7 to 2.5 eV. The diffractive effect pigment may be further coated with a coating which is optically non-active in the visible wavelength region.

An asymmetric pigment including a first Fabry-Perot structure; and a second Fabry-Perot structure; wherein the first Fabry-Perot structure and the second Fabry-Perot structure have a similar hue angle within +/45 degrees is disclosed. Other asymmetric pigments are also disclosed as well as methods of making the disclosed pigments.