I have received emails asking this question. So I will let a great member of the collecting family answer that. From comes this . Now a little more that I know. The metal core is most often brass, so these are often called brass core chips. however the cores have been made with other metals also. I have seen copper and a silver colored metal (steel or nickle ? ). Reliance made many if not all older PMSC chips. A Japanese co. Called Matsui-Gaming Co. Makes many very nice looking chips now. I am not an expert, so if I made mistakes or if you can add more please do so.