Certain Vertices with certain colors

Is there any way to select say 4 vertices and have the area in between them a different color than the area around them? If so how?

If this is not clear, say you subdivide a plane. With the subdivision you select a square (one of the corners). You want this square to be blue, but you want the rest of plane to remain the same color.

Please help me.

Make your selection, go to F9 and under the links and materials tab, create a new material and apply. Then go to F5 and make the material single user and change its colors.
Hope it´s clear enough.