When I was still working, I encountered a lot of questions with determining the specifications of things. When disputes arise, I had to refer it to one of two internationally recognized institutions in the country. PIPAC or Philippine Institute of Pure and Applied Chemistry (Loyola, QC) and the government's Department of Science and Technology (Philippine Institute of Metal Research, I forgot exactly the name, but it is at Bicutan in Taguig). A friend and me agreed that the best way to determine the metal composition of a coin is to get a true coin which can be disposed and have it melted and tested at the laboratory.