The Color Rendering Index [0] measures how well a light source shows the colours of various objects faithfully compared to natural light. Perhaps we also need

The Color Rendering Index [0] measures how well a light source shows the colours of various objects faithfully compared to natural light. Perhaps we also need a dual index that measures how well a pigment retains the same appearance under various light sources. [0] https://en.m.wikipedia.org/wiki/Color_rendering_index https://en.m.wikipedia.org/wiki/Color_rendering_index