They are known as Foreign Exchange Certificates here is an example from 1969 https://en.numista.com/catalogue/note215225.html
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Hope it helps. Welcome to CT
Place your tablet on a soup can, small box etc. Place your coin on a bottle cap on a benign surface, such as grey or black. Light the coin from 10...
@Jackflash Cents were not plated in 1953, so not a plating blister. In 1982 the mint changed cents to a zinc core with a micro thin plating of...
MS65
A good looking coin
1922-D has some struck with a feint D, and some with no D
Welcome to CT It has been explained above. A grease/debris filled die caused it. When a planchet is struck, the metal moves to fill the incuse...
Welcome to CT. Here is a link to a respected numismatic site. The section describes what has occurred to your coin. Bookmark any sites you receive...
Numista describes and images the varieties in the comments section. Click it to enlarge https://en.numista.com/catalogue/pieces977.html
The micro thin piece of metal of a finned rim soon gets folded over and smoothed. If it is a finned rim, this is how it happens....
Info here, there are others to check for also. Screen shot so you don't have to open a link [ATTACH]
@Charitycoincollector Try to do some research on the Saudi Arabia guinea with counterstamps. I don't have time to do further searching, but it...
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Dug up a few more [ATTACH] [ATTACH] [ATTACH] [ATTACH] [ATTACH] [ATTACH]
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