In the above link it is stated that: "
no mint marks were placed on the coins and the design, metallic composition, and date are all the same as the original issue, so it is impossible to identify the origin of any specific coin."
I am wondering what dies were used to strike the coins in San Francisco. Were these obtained from the Chinese mint or was a master or working hob obtained from China. Or alternatively was the Chinese plaster model used to make new dies. In any of these cases it would be impossible to distinguish US from Chinese strikes. Except when some mark was applied to the dies before striking. If no minting material from China was used then new dies would have to be made. One way of doing this is enlarging a coin made in China using a reducing machine (using it the other way around). Then reworking the resulting large model to remove irregularities and then using this new model to prepare new dies. Such a procedure would inevitably result in some minute changes in the coins by which they might be identified.
Also differences may arises in the edge. If a new die was used in the edge reeding machine the number of reeds might be different from that of the original.
It could also be possible to distinguish the coins by the composition of the planchet. If the planchets used in SF have a different origin than those used in China they might have different composition. This would not show itself from the presence of impurities. These can be detected from a detailed analysis like XRF.
The question is what dies and planchets were used to mint the coins in the SF mint. It these were the same as those used in China than identification of the origin may indeed be impossible otherwise it might be possible.
Posted 11/17/2020 9:16 pm
