Tritone Shading

A style of shading (commonly used in comic books and anime) which depicts materials with up to three banded or posterized colours.

Guy1: Dude, how many shades of orange should the character's hair be?

Guy2: Make it three: amber, yellow-orange and peaking white for the gloss effect.

Guy1: So tritone shading it is?

Guy2: Yip.