AbstractColor order systems must be distinguished from colorant order systems and other systematic ways of relating colored objects. Abstract systems require definition of dimensions and scales. A concrete system is a collection of specimens exhibiting properties specified by the dimensions and scales of an abstract system. The accurate production of such specimens requires a complete written definition of the system, including the specification of all pertinent observing and measuring conditions. The choice of materials requires consideration of the spectral and geometric aspects of the optical nature, some aspects of the mechanical nature, stability, durability, availability, acceptability to users, and cost. The value of color standards depends on the precision and accuracy with which they are produced. Efficient production and long‐term reproducibility depend on well‐standardized methods of color measurem