Help please with Ptolemy XII tetradrachm authenticity

I had recently posted this is my Top 10 Ptolemies thread. When it was in auction, the listing said that it weighed 10.72 grams, low but I figured it had metal that had leeched out over time as shown by its porosity. When I weighed it recently, it turned out that the coin was actually 8.1 grams. Definitely not as described and way lower than typical examples in the 13-14 gram range.

It has no seam, does not look cast, and a couple of tiny copper oxide encrustations, which point towards it possibly being genuine. A friend I spoke to informed me that silver-plated imitations were struck around the time of genuine examples with good style and legends. I did a search on acsearch and found just one that’s a similar weight (7.59 grams) that was sold by Agora in 2017, described by them as a “lightweight issue”. The style looks very similar. In addition, my example looks to have what looks like traces of bronze disease in a few of the cracks on the surface, which I’m thinking supports my coin possibly being silver-plated.



The Agora example on acsearch (https://www.acsearch.info/search.html?id=4055414):



Any help with this matter is appreciated, thank you.

 

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Maybe a didrachm?

 

I forgot to add that it is 25 mm wide, typical tetradrachm width.

 

I am pretty confident from your photo that your coin is not a cast. I strongly suspect that it is ancient.

I think your suggestion that it is a fourree is possible. I agree that the areas under the ear and jaw have the look of bronze disease. Have you tried picking at it with a toothpick to see if it comes off powdery like BD?

 

Not yet. Don’t think I will until I figure out what I’ll do with the coin. I don’t collect fourrees (although this one seems kind of interesting), and I suspect that the BD, if it is that, is more widespread underneath the silver plating. And BD can be a hassle if it keeps coming back after being “cured”. I’m leaning towards returning it and getting a refund. The auction house guarantees against “forgeries”; nothing specifying that they have to be modern reproductions. Or at least maybe I can try to argue for a refund on the basis that the actual weight was not as described. There also happens to be no mention of my coin being a fourree/silver plated in the description, just that its an AR tetradrachm.

Any idea on how auction venues typically approach the issue of silver coins that turn out to be fourrees? Or when a coin’s weight is a good amount lower than as what was listed? Are these things they’ll be willing to accept a return for?

 

It depends on the auction house. Any reputable dealer knows that keeping customers happy is much more important that any one particular sale. They should absolutely refund your money because the coin is not as advertised. Although calling it a fourrée is speculation, the difference in weight is indisputable. They owe you a refund and sincere apology. That's how you'll know that you are dealing with a respectable firm. Anything other than that, and they have just shown you that you should never buy anything from them again.

 

If you possibly can figure out specific gravity, do a specific gravity test on it. A coin that large should be doable with a minimum of equipment and a good likelihood of accuracy. You can find some good info, including videos on how to do it, on the Net. It looks good but that weight discrepancy needs to be explained. The weight is way off. I have in my collection a number of plated coins, including one which is an obviously plated Ptolemaic tetra with silver having flaked off in several places. Such coins were made in that place and time. I have no problems having several in my collection. They were part and parcel of Ancient coinage as counterfeiting was invented the day after coinage.