What makes this nail polish glow in the dark anyway?

A. Glow in the dark pigments, or colors, create the glowing illumination.

Is glow in the dark nail polish radioactive or harmful?

A. No, it isn’t radioactive or harmful when applied to fingernails. The FDA approved phosphorescent pigment for nail polish in the year 2000. The "glow in the dark" or phosphorescent pigments consist of very fine crystals of zinc sulfide. Copper is added to the zinc sulfide as an activator. This allows the crystals to absorb light and slowly emit it over time. The slow emission is called phosphorescence.