Certain types of cosmetics contain chemicals that can abrade your jewelry, causing a sort of metallic dust. This metallic dust often appears black and can cause smudges on your skin or clothing. To avoid this problem, put on your jewelry after applying your cosmetics.
Black smudges may also be caused by corrosion due to perspiration, exposure to salts and exposure to hydrogen sulfide gas (present in polluted air, some foodstuffs and industrial chemicals). To avoid these smudges, we recommend that you do not wear your jewelry while handling chemicals or products containing sulfur, and gently polish your jewelry often to remove tarnish.