I did a painting seminar locally late last fall and picked up one of the GW blue shade colors figuring someone might ask me what I thought of them. The two miniatures on the right in the above pic, I used that on to shade starkly highlighted blue colors. It works fairly good. As you see on the green, I did that with a dark green acrylic paint that was heavily watered down. So you really don't need to go out and buy that GW stuff to achieve a shade. But I know people like it so, and I now need to use it up.