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Colour Index™ Classification ~ Overview

The Colour Index™ uses a dual classification system.

Colour Index™ Generic Name (often abbreviated to CIGN).

The prime descriptor, in that it is the one most commonly used in discussions by colorant users and is the one easier to remember, is the Colour Index™ Generic Name (often abbreviated to CIGN). This is related to the application process.

Colour Index™ Constitution Number (often abbreviated to CICN)

The other descriptor is the Colour Index™ Constitution Number (often abbreviated to CICN) which is chemical-structure related.


These terms and definitions have been agreed by the Colour Index™ Technical Boards who are volunteers who help to maintain the quality and integrity of the Colour Index™ (C.I.). These Boards are split into having reponsibility for two areas

Part 1 covering pigments and solvent dyes, widely used in the paint, plastics, ink and other coloration industries.

Part 2 covering dyes used in a very wide range of industries. The main dye classes are: acid, basic, direct, disperse, food, fluorescent brightener, mordant, reactive, sulphur and vat, plus several other classes of minor or historical importance.

Information given here will help subscribers and registrants understand the various terms that are used.


While the greatest of care has been taken to ensure that this publication is free from error it is inevitable that some mistakes will have gone unnoticed. It is hoped that anyone noticing a mistake of any kind will immediately draw this to the attention of the Society. We shall try to put any such mistakes right as soon as possible.

We rely on the co operation of dye and pigment manufacturers who keep us informed about changes to their ranges and allow personnel to give their time to ensure that the Colour Index™ fulfils its aims.

We are always looking at ways of improving and developing the Colour Index™ and comments are always welcome.

If you feel you should be registering your products to be able to use the C.I. nomenclature then contact us.