Cleaning Gold Coin

I don't know is this just a illusion, but it seems to me that gold coins preserved in mud for centuries doesn't seems to change at all their gold appearance, but once unleashed from mud, and on air, they do get some darkening, some of them just slightly and some of them a lot. It's not 24 carat gold, it's 22 carat so there is probably alloys what make gold coin darken after exposed to the air and oxigen. That is only my amateur opinion, but from experiance. Could also be that at first sight, coin looks brighter to me than it realy is, and more I'm looking at it, more dark details I see. Don't know.

Show us a before pic and then when decide how to proceed post the after. I do not have any gold coins and I am not sure how to restore / conserve one but I think I would try soaking it in distilled water. Just a plain old water soak might release the contaminates; in fact I think it should; IMHO. Also I would avoid rubbing across the coin to avoid hairline cleaning marks that could devalue your coin. I look forward to seeing pics!

The only thing that I would do to attemt to remove any dirt is to wash it in your hand with warm water and some mild dish soap and than pat dry with a soft cloth. This is a very interesting coin that no one has been able to come up with a reference for. It's either an unlisted rare example or an extremely well made fake.

That is Diocletian Aureus Quinarius, it's almost unique coin, because since Diocletian monetary reform, half aureus have been disappeared. And it is 100% genuine.
As well as this other, that need dirt cleaning. Also rare coin, and well preserved to.
Claudius Gothicus Aureus, 5.4 g

Dionysos, yes I know. That one, is also best match that I could find, but from NAC they told me that this is not unique. Guess that they know for some other such exact coin from their customer which is not listed, but they have it in their private lists.

I didn't ask details, they just told me that it is not unique.
Well, for buying a house in Croatia you must first be a lawyer, otherwise you could easily go to jail. In Croatia, we all are lawyers, and still, there are big waiting lists for jail-house. :)

Kinda stealing the thread, but I would suggest Pula. Wonderful place, but I do not know the laws regarding foreigners buying in Croatia.

Great Roman ruins as well.