Gold hallmark on gold jewlery from Rome

by John Frusha
(Baton Rouge, La.)

I collect micro mosaics and have several that are mounted in gold (14K I think). They have the Papal seal of the miter and crossed keys stamped on the c-clasp or the pin. I came across an article that I can not find that said this was the gold hallmark of Rome. If it was just crossed keys it was less than 14K, keys and miter it was 14K, with addation of the head of a wolf it was 24K?? Can you help with this hallmark and/or a reference for me to find any additional information. Thanks, John Frusha