Abstract: In a colorimetry system, the test surface, the color of which is to be measured, is illuminated by a fiber optic cable. Light transmitting ends of the optic fibers of the fiber optic cable are uniformly distributed into an annulus with the transmitting ends of the optic fibers pointed inwardly at 45 degrees toward the axis of the annulus. A light pipe, or a second fiber optic cable, is positioned to have one end on the axis of the annulus to receive diffusely reflected light from the test surface and transmit the reflected light to photodetectors through different color filters. The output signals of the photodetectors are applied to the colorimetry console which converts the photodetector signals to standard color index values.