If you need to tone them down a bit you can use black shoe polish, the paste type. Try a dab of it, and rub it in good, trying to keep the color consistent. Then wipe the grips off several times to remove any excess. I've found it helps to have the grips pretty warm (like shoes) to get a bit of penetration. After several wipings, I've never had an issue with staining on clothes, but you might want to try this with an old set of grips to start with in case you don't like it, or in case the original formula has been changed and I'm not aware of it.