Altering Vertice Colors

I would like to take a triangle and access each vertex and color it myself with the VertexColor command. I looked through the archives but I might have missed it. Can someone give me a hand here?

1______2
...\.........|
.....\.......|
.......\.....|
.........\...|
...........\.|
.............3

Look up the TriangleVertex command ...

If you're looking for solid colour on each triangle, avoiding gauraud shading then all the vertices in the triangle will need to be unwelded.