the invention is a colorimeter for measurement of the color of an object . the colorimeter comprises a hand - held probe which is similar in size and shape to a large writing pen and provides the capability of measuring the color of a spot or target on , or within , the surface of an object . a measurement is made while placing the tip of the probe against , or in close proximity to , the surface of the object . the calorimeter generates from a single measurement three color data points representing the reflectance of the spot measured at the wavelengths of three primary colors . from those data points , a microprocessor can perform analyses yielding a single color value represented in various standard formats , or it can compare the measured values with a preloaded table of values . the colorimeter can then present the results on a liquid crystal display . the colorimeter contains multiple light emitting diodes for successively emitting light of different colors toward a target , a light sensor for receiving light reflected from the target , and a light pipe for directing light from the leds to the target . the display may be an integral part of the probe or contained in a separate display module connected to the probe by an electrical cable .