Within the international English system, the so-called Colour index, each pigment is indicated with a pigment name and pigment number.

This makes it possible to ascertain which pigments are incorporated in certain colours as well as the chemical composition and properties of those pigments. It is mainly the pigment names that are of interest to the artist.

Example: PW = Pigment White
PW4 (pigment name) = zinc oxide - 77947 (pigment number)

Examples:

PW   - White pigments       PW6     - Titanium white
PY    - Yellow pigments      PY35    - Cadmium yellow
PO    - Orange pigments    PO34    - Azo orange
PR     - Red pigments         PR112  - Naphthol red
PV     - Violet pigments      PV19   - Quinacridone rose
PB     - Blue pigments        PB29    - Ultramarine
PG     - Green pigments     PG7      - Phthalo green
PBr    - Brown pigments     PBr7     - Natural umber
PBk    - Black pigments      PBk11   - Oxide black