This article describes recent developments at the National Institution of Standards and Technology in the colorimetric characterization of pearlescent coatings. The goal of this research is to develop a measurement protocol for the accurate color characterization of these coatings using an understanding of their scattering mechanism as a guide. A large ensemble of bi-directional reflectance measurements on a series of pearl interference pigmented coatings show general trends in the color variations with illumination and viewing angles. These measurements were used to define a set of geometries (illumination angles of 15degrees, 45degrees, and 65degrees and aspecular angles of 15degrees, 35degrees, 45degrees, 70degrees, and 85degrees) to characterize the angle dependent color travel observed in these coatings. (C) 2003 Wiley Periodicals, Inc.