Contemporary counterfeiters were always looking to make fake coins from inferior metal with perhaps a surface layer of silver. A primary checkpoint is therefore to weigh any suspicious coin. If it is more than 6% underweight be concerned.
Anchor mintmark coinage can often be underweight by this amount and still be genuine, such was the pressure on the mint. Allow up to 10% for this type of coinage, before becoming suspicious. It is also not unknown for a fake coin to be overweight but usually this is not a contemporary forgery. If more than 3% overweight be concerned.
Victorian electrotypes often are not the correct weight but very close. They often display surface dimples or pinpricks of metal to distinguish them from the real coin.
Correct weight is a good point in favour of a coin being genuine.
In today’s market a modern fake coin can easily be the correct metal and the correct weight. If packaged in a plastic container it it often nearly impossible to either weigh the coin or closely inspect the edge for hints of whether it might be fake. In this situation one should proceed with caution. Check the fine detail on the coin, the detail in the mintmark, the devices for sharpness, the digits of the date etc etc.
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