Not all Ancient Silver coins are made from solid silver.
This does not mean that the coin is either a fake or an ancient attempt to fake the coin. First of all, I will explain just what I mean by the coins not being solid silver when, for reasons explained soon, they perhaps should be.
To keep things as simple as I can I will take two Roman coin types as an example. The Denarius and the Antoninianus. In theory, both of these coins should be solid silver, especially the Denarius. However, this is not always the case.
The Silver Denarius.
A lot of silver Denarius are made up of solid silver, but there are a huge amount which are not. Some are made with a copper alloy core and are then dipped or washed in silver, hence the term 'silver wash' or 'silver dipped' this is all very normal and the coin is still classed as a silver coin. Some are made using 'debased' silver, again this was very normal practice. It is not always easy to tell if a Denarius is a solid coin or has been 'dipped'. But in either case you have not been robbed if you were to have bought one of these coins. It is still a very genuine coin. Take a look at the examples of Denarius below. The first coin, to the left, is solid silver. The second is 'washed' or 'dipped' silver. Both coins are 100% genuine and are both classed the same, as silver Denari.
The Silver Antoninianus, 'double denarius'
The silver Antoninianus, or more commonly known as 'Ants' are well known for being silver washed and very debased silver coins. Take a look at the three Ants below. From left to right, the first coin is a solid silver coin. The second is a copper alloy coin which has been 'washed' in silver. The third coin has become so debased that it just looks like a bronze coin, it has not even been dipped in silver, yet this third coin will still have a small amount of silver in it.
It is worth mentioning at this point that even some ancient Gold coins were not made from solid gold. Some of these coins, mainly the Roman Aureus, actually have an iron core and washed or dipped in a good layer of gold. But they are still genuine coins. Not fakes or forgeries either modern or contemporary. It is also worth a quick mention that some of these gold coins even had a lead core, these of course are contemporary forgeries.
So why have a silver coin with a non silver core?
And why make a silver coin which is so debased that it looks like a bronze coin?
The answer to both of these questions is pretty much the same. Lets take a short trip back in time. I just use the Roman period here as an example but the lack of silver in coins goes back much futher than the Romans, and indeed continued upto resent times.
We must remember that like everything else, silver as well as gold, was a commodity. The Roman empire was vast and the Roman currency dominated that vast empire. Of course they had access to silver mines as well as the silver items taken in times of war as 'spoils'. There was no shortage of people to work in these mines and there was no issue with the production from raw materials to silver ingots. The real problems were things such as wars, there was always a war going on somewhere. Then there were times of famin and decease, there was also a lot of this going on behind the scenes too. The economy was not good at times. Problems with transporting ingots to the place of coin mints without them being robbed or lost. There were times when silver was just in short supply. So to overcome this problem coins were 'dipped' or 'washed' in silver. Towards the latter part of the empire as Roman grip on its vast empire was loosening, the coins tended to become more and more debased as supplying silver became a lesser priority over ensuing battles with Barbarians.
So thats basically why you get these types of silver coins. They are 100% genuine and not fakes, in this context at least.