So through out the book new eye colors of nico's will be introduced so here is a list

Black-Anger and depression

Dark Brown-No Emotion just neutral

Golden Brown-Happiness

Hazel-Deep Affection

Light Grey-sadness

Gold-romantic love

Pink-aroused

Red-dangerous

Green-distressed

Teal-worry

Dark Grey-tired

Orange-suprised

Magenta-family/friends love

Yellow-annoyance

Blue-embarassed

White-scared

If I add more I'll update the list