Colour Index Numbers

Pigments are given a color index number according to the chemical structure.
The table below shows the ranges and categorys.

Colour Index International is a reference database jointly maintained by the Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists. It was first printed in 1925 but is now published exclusively on the web. The index serves as a common reference database of manufactured colour products and is used by manufacturers and consumers, such as artists and decorators.

Colorants (both dyes and pigments) are listed according to Colour Index Generic Names and Colour Index Constitution Numbers. These numbers are prefixed in Brazil and various other countries with C.I. or CI, for example, CI 15510. This abbreviation is sometimes thought to be CL, due to the font used to display the information. A detailed record of products available on the market is presented under each Colour Index reference. For each product name, Colour Index International lists the manufacturer, physical form, and principal uses, with comments supplied by the manufacturer to guide prospective customers.

For manufacturers and consumers, the availability of a standard classification system for pigments is helpful because it resolves conflicting historic, proprietary, and generic names that have been applied to colours.