You clean a Chinese coin by immersing it in warm soapy water. Rub any stick dirt with your fingers away from the center to the edges. Rinse the coin and check for any more dirt and rinse again if okay. Place it on a towel to dry and if the dirties not gone, keep soaking the coin one at a time and rubbing the dirt off with your fingers. Store only when dry and handle by using the sides. Read more details at coins.about.com/od/caringforcoins/ht/cleancoins.htm.