Mint State Ancients

In the case of the Rhodian Didrachms, indeed that was the explanation that was offered for them. I still just felt uneasy about them, but I didn't say anything, because it was impossible to be sure.

If you are going to expose something that you feel is wrong, you need indisputable proof.

I have an Alexandrian Tetradrachm of Ptolemy X11 of Roman Egypt that was unrecognisable when I bought it for very little. A specialist ancient coin dealer offered to clean it for nothing, because he was just as curious as I was. It was put into a weak solution of hydrochloric and sulphuric acid such that any reaction would proceed slowly. It proved to be of very good silver and genuine, but it still cleaned up with a sort of 'patination', quite unlike the Rhodian Didrachms I saw.

Both patination and wear/damage are easily simulated by someone selling fake ancient coins. Anyone buying worn or patinated coins on the assumption that those are signs of authenticity could be in for a nasty surprise.


I'd say that was the result of using hydrochloric acid. HCl doesn't react with silver metal itself but can react with silver compounds on the surface (such as silver sulfide) to produce silver chloride, also known as "horn silver". This will tend to form a thin layer in the spots previously occupied by the patina. AgCl is insoluble in water and just about everything else, so it won't wash off once you take the coin out of the solution, but it will decompose into elemental chlorine and silver on exposure to light, turning the surface of the coin darker and "recreating" the patina more or less where it had been before.

I suspect many hoard coins are cleaned using basic jewellery formulations like Tarn-X or Jeweluster. This would strip the old patina off completely. Repatination of such coins is normally done by application of sulfur jelly, or some similar agent. "Deller's Darkener" is the usual formulation sold by coin supply stores. Obviously, fake coins can be patinated in much the same way.

Wear and damage can be simulated simply by jostling a pile of freshly minted coins together for awhile. Even the famous counterfeiter Becker knew way back in the 1700s that "taking his boys for a ride", by tossing them into a box full of iron filings attached to his carriage, made them more acceptable to the gullible collectors of his day. A gemstone tumbler would work just as adequately today.

The Rhodian didrachm I use for my avatar is nicely patinated, but I doubt it came out of the ground looking like that; it was probably heavily tarnished. First it would have been stripped down to bare metal in the cleaning process (it probably looked "mint state" at that stage), then repatinated - either artificially, or "naturally" by sitting in someone's coin cabinet for decades. I don't really know, since I don't know its provenance beyond the dealer that sold it to me.

I personally don't like, and don't use, the terms "mint state" or "uncirculated" for ancient coins. These terms mean "just as it was minted, entirely undamaged and unchanged". That's just not possible for an ancient coin (except perhaps for gold), because all ancient coins (except perhaps for gold) have been cleaned, and cleaning is damage. gEF is as high as I'm prepared to go.