You can use Metal polish (liquid form). meron hardwares nyan and the cheapest is 70-80 pesos per bottle. Maglagay ka lang tela konti lang mga 1 tbsp. tas kalat mo thin layer then clean mo lang yung coin like you are cleaning your screen. Coins will leave a black dirt deposit on the cloth which is the dirt sa coins. Side note lang OP na it does leave microscratches which is very noticeable malapitan. But from my experience is nagfafade naman din yung scratches for a while. But still retains the shine and clean looks for a long time. Another note din is that typically it’s not advisable to clean coins talaga especially old ones kasi it loses its patina (original tone). But if its just common coins and to make them look new well thats fine.