Ancient Coin Grade Question

[Robert1963]

I have an ancient coin NGC Grade AU. NGC ID Number 4252957-024 and my question is that it has a, I don't know what to call it, place where it says "Silvering" and I don't know what that means. Did they silver plate coins back then? I wouldn't think so, but, if anyone can help me with this I would greatly appreciate it.

[physics-fan3.14]

4 hours ago, Robert1963 said:

Did they silver plate coins back then?

Yes, that's exactly what this means. 

Emperors found out that you can take a really cheap bronze coin, put a bit of silver on the outside, and make it into a more valuable coin. It's kinda like how the US uses a basically worthless copper-nickel clad coin, but passes it as 25 cents. The intrinsic value of the coin is very low, but its an easy way to print a lot of money. 

[Robert1963]

Thanks, I thought that might be the case but wasn't sure. It's pretty trippy that they did that 2000 year ago.

[Conder101]

There are several ways to "silver plate" a surface.  Today we use electroplating.  Back then they could use the dip method of dipping the coin or planchet into molten silver but that would apply a pretty thick layer, more than we see on such coins and probably more than they would want to apply.  One method of applying a very thin silver layer was to rub the planchet with an amalgam of silver and mercury.  The mercury would also bond to the surface of the copper/bronze planchet and leave a thin coating of the amalgam on it.  It would then be heated vaporizing off the mercury and leaving a very thin plating of silver on the surface of the planchet.  After striking the coin would be pickled in a mild acid to remove oxidation leaving the white silver surface.

[physics-fan3.14]

With a little Google-fu, you can find some very interesting scientific articles examining the exact composition of these types of coins. Some of them, they cut them in half (low value coins, of course!) and did spectrographic analysis on the compounds. There is some pretty interesting metallurgic data from these studies, if you're into that sort of thing. 

[Robert1963]

All of this is very interesting. I would have thought that silver plating would have been to much trouble to be worth it back then. I'm a collector of US rare and modern coins and just started buying ancient coins so I'm out of my element here. I guess I'll have to spend the time learning about them like I did with US coins so I buy them wisely. I don't buy ancients for investment but my family seems to be more impressed with them than the US coins. Frankly though I'm spending most of my time and money on US coins as that is my passion.

[Conder101]

Often it was done to hide the fact that the coins were becoming more and more debased.  The coins you see that were silver plated were st one time solid silver of high fineness.  The debasing eventually reached the point where they were copper or bronze with a silver plating to make them LOOK good.  Same reason we went with clad coins in 65 and copper plated zinc cents in 82, an attempt to make it look like the coins were still good quality.  Same reason why if they go to a copper five cent piece it will probably be nickel plated so it still looks the same.

[coinman1794]

On 12/5/2017 at 1:36 PM, Robert1963 said:

I have an ancient coin NGC Grade AU. NGC ID Number 4252957-024 and my question is that it has a, I don't know what to call it, place where it says "Silvering" and I don't know what that means. Did they silver plate coins back then? I wouldn't think so, but, if anyone can help me with this I would greatly appreciate it.

In 244AD, Gordian III struck the last silver Denarii, and the denomination was replaced by the Double Denarius (or Antoninianus), due to inflation making the single Denarius impractical. By the mid-250s AD, they were striking bronze coins and applying a coat of silver to them, and silver Double Denarrii began to disappear as the monetary system started collapsing. Today, the silvered coins are evaluated by how much silver remains on them, and those with great silvering are considered special.