Strange look to UK coins 1815-1820 [resuelto]

Hi

these are George 3 coins from UK. Years 1815-1820.

all should be made out of silver. Any idea why they looks so dark, almost like copper?

are they fake?

There were lots of forgeries of the silver coins, they were either copper or brass painted silver. I have some examples in my black museum or forgeries. 

Please give more precise measurements for each coin and their respective links to the numista coin pages.

Silver coins .925 can look like that, so please inform us better.

6 Pence km 665 2.4 grams. originally 2.83

N#13167

½ crown km 672  12.18 grams. originally 14.14 

N#13169

3 shillings.  14.26 grams. originally 14.7

N#16764

They are obviously contemporary pot metal cast forgeries. It was a cottage industry in those days, not only in England, but all over Europe. 

Every Inn keeper knew to check every silver coin by a a variety of means, shall I quote Dickens for you - “John Willet did as he was desired; for on that point he was seldom slow, except in the particulars of giving change, and testing the goodness of any piece of coin that was proffered to him, by the application of his teeth or his tongue, or some other test, or in doubtful cases, by a long series of tests terminating in its rejection.”

Great 

with your help, found this web

https://www.predecimal.com/forged/georgeiii.htm

Counterfeiting was rife at the end of George III reign, if caught the counterfeiter was transported to the penal colony in Australia or even hanged. But not even those severe punishments would deter the determined counterfeiter from plying his trade