Warm soapy water is the way I used to clean them but it was a pain to get all the soap off. The more I rinsed it, the more soap it made. I read on a granite company website that you could use The Works glass cleaner. I did find it at Meijers (but it's not sold everywhere). It's a gentle glass cleaner with NO AMMONIA ~ that's the key. I guess if you use ammonia on your granite, it could strip the shine. No matter what, I LOVE my granite!