A Pigment is a color additive which does not dissolve into its carrier and is not staining (except in really high concentrations in which case it could).  Pigments suspend in their carrier.  Pigments are flat and non-shimmery. They tend to be opaque. 

Dyes dissolve into a carrier (for the most part) and can be staining.  They are also brighter in hue.  They tend to be flat, non-shimmery and somewhat translucent.

Pigment companies will color Mica with a pigment (or sometimes with a dye) to produce the colored micas which you see all over our website, as well as in all kinds of makeup.  A lot of people call this blend Pigments, but really they are pigments mixed with shimmery mica!

Additional Resources:

- What is a Dye, Pigment, Mica?

- Why Eyes, But Not Lips?