The colour index is the primary systems used in pigment identification. The colour index name identifies the colour as a pigment (P) or dye (D) by it’s general hue (B=blue) and assigned number.
For example, Dioxazine Violet is: PV23
P = PigmentV = Violet23 = Assignment Number
The colour index name refers to a specific pigment, and blended colours will be marked with each of the pigments present in the blend. For example, the colour blend for Alizarian Crimson Hue is: PR 170 (Naphthol Red Medium), PR 101 (Transparent Red Iron Oxide), and PV23 (Dioxazine Violet).