I hope someone can help me. I just began wearing a silver marcasite initial pendant that I purchased several years ago. I love it and receive numerous compliments everytime I wear it. But when I wiped it with a silver polishing cloth (from Yurman purchase), the cloth gets completely black. I keep wiping and wiping and can't seem to get all the black off the pendant or chain. What is the best way to clean this piece? It looks great so imagine how wonderful it will be when it is clean. TIA!