Months ago I hatched a plan to change the color of 2 pairs of shoes I had purchased. They started as the same reddish brown color. I wanted to take the loafers in the direction of medium brown and the wing tips toward burgundy. A few months and a few polishes later the colors of each pair of shoes is easily distinguishable. I expect the difference to further develop over time, but we shall see. I am quite happy with the colors in their current state.
If you were wondering, the primary tool in my madness is that of Saphir shoe polish. It really is the best you can buy, to my knowledge (Justin over at The Shoe Snob also has some great shoe polish as well). The pigments are rich and the stuff is easy to work with. Expensive? Yes. But worth it? Yes.