The history of philately (the study of postage stamps) shows a gradual increase in the use of color in the inks used to produce postage stamps. Low chroma reds and brown were introduced through the use of natural plant dyes, such as indigo and animal dyes. Today, many synthetic organic dyes and pigments produce much stronger stamp colors. This paper presents a table that lists the various dyes and pigments that are currently being used by the U.S. Postal Service for the printing of postage stamps. A section on the origins of color includes a discussion of the molecular and atomic composition of various dyes and pigments. A section on luminescence notes that the luminescent properties of certain papers and inks have been used in two important philatelic applications. The first application is the use of phosphors on the surfaces of stamps, so that facer/canceler machines can locate and cancel the stamps. Phosphors are materials that give off visible light when exposed to ultraviolet radiation. Another philatelic application is in the detection of fakes and forgeries. Since ultraviolet will reveal many differences in materials not seen in visible light, it can often be used to detect repairs, alterations, and forgeries. The paper concludes with a discussion of types of adhesives used in postage stamps, with attention to the three adhesives used in U.S. postage stamps: gun arabic, dextrin, and polyvinyl alcohol. 9 figures, 3 tables, and 11 references