Argyria is a condition that is characterized by bluish-grey to slate-grey staining of the skin and mucous membranes caused by deposition of silver particles in the skin. One might get excessive exposure to silver through medication, occupational work, dietry supplements and surgical procedures. Clinical procedures include grey-brown staining of the gums, hyperpigmentation. Its a rare condition in which pigmentation is permanent and untreatable. Some research suggests hydroquinone to reduce silver granules in skin.