0,5. The metamerism index is not suited for determining the absolute colour difference or colour consistency of a given specimen at change of illuminant.The colour difference under the reference illuminant is to be measured in colour coordinates L*, a* and b*.Excluded from this method are organic coatings producing fluorescence and/or which are multicoloured, pearlescent or metallic.Establishing a reference as well as the magnitude of an acceptable colour difference are not covered by this method.Two methods are given in this document:a) instrumental colour difference measurement using a tristimulus colourimeter;b) instrumental colour difference measurement using a spectrophotometer or equivalent.It is advised that care is taken when measuring e.g.- textured surfaces;- fluorescent coatings;- metameric coatings;- multi-coloured, pearlescent, metallic or special colour effect coatings." />