This is about "assaying" metals. It's what Archimedes was working on in the "Eureka" time.
You'd want the density of the item. It'sd volume could be found by water displacement in a Eureka tin. (It's got an overflow spout for displaced water).
Then it's the mass. This is the weight divided by gravity.
Mass/volume is density. The thing should have a density between that of copper and that of gold. Exactly how much is calculable ... Archimedes said so !!!