This standard specifies a general test method for comparing white, black and chromadizing pigments with reference pigments in natural color systems using the chroma method. Color differences in pigments can be measured objectively and accurately to ensure conformity and mass of pigments. The standard describes in detail the instruments, operating procedures and data processing methods required for the test. In addition, the standard specifies the details of changes that should be referred to this method in the specific pigment product standard and may be required. When the general method is not applicable, a different photometer method should be specified for Color comparison.