Dyer's color triangle (silk).

Mayer-style triangles continue to be used as tools to test colors and match shades for pigments and dyes. This example calibrates red, yellow and blue shades of Irgalan dyes, a type of synthetic dye often used by art conservators, but any three colors might be combined in this system.

Source: Made by Shirley Eng for the Conservation Laboratory of the Museum at FIT (Fashion Institute of Technology).