I have a cream Ferragamo Croceira handbag, which is made of a pebbly kind of leather and bronze hardware. I have noticed that the bronze is now rubbing off on the nearby leather and leaving dark marks! Does anyone know of the best way to get these out? I have tested a small patch with cotton buds dipped in some warm water which seems to work however the white stitching has also darkened and I can't get it clean. Any help/advice would be much appreciated!