Repair silver dollar patent

There is this thing, but I don't believe it. Some things can't rely on instruments. His principle is to measure the density of silver dollars. The density of fake silver dollars is smaller than that of real ones, and sometimes you can't feel it when you get started. You can do it with instruments, but if you judge by him completely, you will definitely suffer, because I have never used it, so I don't believe in his magic for the time being. It is better to rely on your own eyesight and sincere communication with your peers. It's endless. Grind it well.