MESH MODELING: My 3d model is 2 colors (without textures applied)

I’ve been trying to figure out how to fix this for some time but point-pulling and deleting/re-drawing faces doesn’t work either.

The bust of my 3D model looks like this without any textures applied:

I have a Subdivision Surface modifier applied to the base mesh, but toggling the modifier on/off doesn’t change the coloration or the strange indentation that appears on the borders where the color changes.

I don’t mind much if it is two colors. The reason I’m posting is because where the color changes, the surface of the mesh is not smooth. There is some sort of stepwise indentation.

^ With subdivision modifier turned on

^ With subdivision modifier turned off

Has anyone seen this problem before? Do you have any suggestions to fix this?

Thank you!

Inconsistent normals. Some faces are pointing inwards and some are pointing outwards

Remove any double vertices (select all vertices and W / remove doubles)
Select all vertices and recalculate normals (Ctrl+N)
Flip any selected face with W / flip normals

Richard, you are the absolute best! Thank you so much, this worked!!!