Cyprus 5 Mils 1955 In Copper-Nickel. Could It Be?

@sel_69l: Thanks a lot!

Sap: I agree that is an obvious possibility. I have quite a few plated coins and off metal strikes. As you would expect, the plated ones in my collection are much more common.

Sometimes, but not always, there are tiny unplated spots on a plated coin that show up, indicating the contact points where it was supported in the plating solution.

Bronze has a density of 8.88 g/cc, and copper nickel 8.91 g/cc. In a coin weighing in the region of 5 grammes, the difference in weight attributable to the different alloys is only about 0.017 of a gramme, or about 1/3 of 1%. (1 in 300).

Wear could also account for this type of difference in weights, or even the amount of plating on a bronze coin.

If a wrong planchet was erroneously used, the error coin would have the weight of the wrong planchet, which could bear no relationship to the intended bronze coin.

Basically, weighing is not the only information to an investigation of this type.

Unfortunately, one of the tests to tell if a coin is plated or is an off metal strike, is to put a tiny nick in the rim of the coin, and examine the mark with a 20x loupe, that has no colour aberration. The colour of the metal in the nick may be revealed. As I am also a gem facetor, I have one of these types of loupes. It is a pity that a coin has to be injured in this way for examination.