Here are the closed up images, as best as I am able to take.
I apologise I followed up with lengthy thread and more photos as well. Here the Reverse:
Looks like gas occlude across the diameter? View from the other side
Otherwise the ping test is either Great or Good (I use Morgan which is free because I am not a subscriber). I am not sure a Silver Cast would give the same frequency as it is a function of density and more importantly Modulus of Elasticity.
Diameter 38.7mm, thickness measured at raised Rim is 2.4mm and thickness measured at background field is 2.2mm.
For the most part, classic USA silver is 90% silver with the other 10% being copper. Specific gravity can support that. The coin in the OP could have a mix of quite a few metals (maybe as much as 11). If silver, as the gadget shows, my doubts remain. Take the reading on the gadget. Then see if specific gravity is 10.31 I appreciate the close-ups of those odd marks. I snapped a bunch of those when making this binder:
Short story. I remembered my in laws acquired 2 of these Fat man dollars, when someone living in the same village decided to sell their family fortune, having good amount to sell and raise money for whatever causes of their own matter. My in law bought these for 100 yuan a piece back in the mid-90's, about $15 US dollars each with current exchange rate, not knowing if these were genuine or not, it later came into my possession once they knew I collected coins, and I had these 2 coins today still reside some place in my albums.
This post had raise my curiosity when reading Albert comments, if the possibility of genuine Fat man dollar had used various alloys mixed in when many of these were strike, beside the silver content, the lack of quality control back then would be questionable.
Manage to get hold of a subscriber to ping test the coin with the correct 1920 FatMan Dollar Apps. I have no idea what alloy formula can emulate exact ping and pass Sigma for .900 Ag (Sigma doesn't have .89 Ag selection)? I will perform a specific gravity test when I have the necessary apparatus.
In between, the frequency spectrum looks much cleaner compared to when using the wrong Morgan Apps earlier in the thread.
One aspect of a ping test some don't think about is the duration. I have fakes that ping nicely but the duration quickly falls off way too soon. The spectrum above shows 7 peaks instead a single. One single peak showing the harmonics trailing off. I'd be curious how the coin reacts in the presence of a suspended N-52 magnet. Or on a magnet slide.
I dismantled an old spoiled Hard Disk Drive to remove the Neodymium magnet inside. Tested on this coin.
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I balanced the coin on my finger tip while avoiding direct contact. There isn't any knocking or touching of the magnet against the coin, if there is the coin would dropped from my finger pivot. Moving back and forth the magnet creates a changing magnetic flux to cause the rocking of the coin. Otherwise the coin is not attracted to the magnet.
The video does not show if the coin is or is not diamagnetic. Suspend a proper N-52 magnet pair and approach the pair with the coin to see if it "pushes away" having an opposing magnetic field.
Diamagnetism is the property of materials that are repelled by a magnetic field, due to the induced magnetic field in the opposite direction.
I do not have a N52 slider. But it rocks because it repels. If it is paramagnetic it will weakly attract e.g. Tungsten. The video clearly show it is not Ferro.
Wish I have access to an XRF metal analyzer to measure and breakdown the elements composition. I don't.
Thanks to your photo illustration. Need to buy a proper N52 to do. Good Night.
Readily found in many sizes. Something about diamagnetic coins is that the idea is to see if a reaction does or does not happen. If it does not, unlikely the coin is silver. But if it does, it is not proof the coin is silver at all. Other elements can give similar or confusing results such as aluminum and copper. That's why follow-up testing by other means is needed as a next step or two.
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Posted 02/20/2025 3:26 pm
