Curious why your nails have a stained yellow look? According to professionals in the industry biz, wearing dark nail polish can be the answer. Darker color polish can cause a chemical reaction between the nail polishes coloring agent and the nail plate, according to nail queen Sally Hansen. This can happen in a matter of days or weeks of wearing the nailcolor. If you love your darks, but don't like the yellow-look, use a light buffer to rid nails of yellowness and use a base coat rich in vitamins to reduce the yellowing of nails.