The purpose of this article is to assist the clinician in establishing a clinical approach to the diagnosis of focal, flat pigmentations of the oral mucosa. These pigmentations include lesions that may be blue, purple, red, black, or brown. The etiopathogenesis may be variable and the pigment may originate from an exogenous (extrinsic) or endogenous (intrinsic) source. Exogenous pigmentations are of a traumatic or iatrogenic origin. Intrinsic pigmentations are either vascular or melanocytic. Clinical approaches include a thorough history and physical exam coupled with diascopy (blanchability), radiographs, and tissue examination (biopsies). An algorithm is presented to clarify the diagnostic approach. The diagnosis may vary from pathologic entities that require no treatment to others that may involve malignancies and their associated management. It is therefore extremely important that these lesions are identified and properly managed in an expeditious manner.