1.1 This practice specifies the equipment and procedures for visual appraisal of the colors and color differences of opaque materials that are diffusely illuminated. These specification are of critical importance in color matching. This practice requires judgments by observers with normal color vision. 1.2 Critical visual appraisal of colors and color differences of materials such as metallic and pearlescent paints requires illumination that is nearly a geometric simulation of sunlight, because such directional illumination permits observation of the glitter and goniochromatism that characterize such materials. Such viewing conditions are beyond the scope of this practice. 1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.