The following was stated on a group that I belong to: "When the coin blank gets loaded, inbetween the die faces, it has a certain size and a specific weight. Once it is "SMACKED" as you call it, with several tons of FORCE (to imprint the pattern on both sides), certainly the weight didn't change ---> but the size changed slightly. Thus "the newly coined - coin has a slightly higher density than its orginal blank..
density (ro) = Mass/Volume.
If volume decreases slightly and the Mass stays constant, then density will increase slightly.
I don't mess around with graduated cylinders and water. You can if you want. I size the coin or bar and calculate the volume. It takes a little time but it gives you a chance to examine the item closely up front and personal like. If there is any funny business from the merchant -- they start to get real nervous. You can usually pick up on that.
I will weigh the item. I will even use their scale. I carry a medimum size nut for a reference. I know the weight of my reference and if that weight doesn't show up on their scale then there is no sale..
My reference NUT weighs 30 grams which is very close to most coins of the one ounce variety.. If I am looking at a bar then I carry three nuts." Could this be true? I have a hard time believing it, even disregarding his spelling.
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