Behlen's Solar Lux Medium Cherry. To darken it you can mix in some of
the Medium Red Mahogany Solar Lux. To lighten it, you'll want to use
the Behlen's Reducer.
If you don't need to go very dark, sometimes the Watco Cherry or
Fruitwood Danish Oil will do the trick, too.
You're going to have to experiment to figure out what works best.