<p>A method of measuring the lustre of a surface having a metallic appearance comprises a) determining the intensity of the various wavelengths of light reflected from an area of the surface; b) producing from the reflected light measurements a set of CIE L*a*b* coordinates for the surface with the specular content of the reflected light included and a set of CIE L*a*b* coordinatess for the surface with the specular content of the reflected light excluded; c) converting each set of CIE L*a*b* coordinates into its tristimulus values; d) converting the tristimulus values for each set of CIE L*a*b* values into spectral reflectance data for each set of tristimulus values; and, e) converting the spectral reflectance data for each set of tristimulus values into a lustre measurement for the surface which is a function of the difference between the sum of spectral reflectance data for the set wherein specular content is included and the sum of spectral reflectance data for the set wherein specular content is excluded.</p>
