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| - U.S. Pat. No. 3,438,796 and U.S. Pat. No. 5,135,812 describe, for example, metal lustre pigments having a central essentially non-transparent aluminum film coated on both sides in alternation with dielectric films of low refractive index, such as silicon dioxide or magnesium fluoride, and with partially transparent metal films, such as films of chromium or aluminum, for example.
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