US Gold Error

Chicco, nobody here was trying to be rude to you at all, only members offering opinions, and great, educated opinions at that . The fact of the matter is that it IS 99.999% certain that it's not a US minted coin, or at least not an error from 1858, it's either altered or more likely a jewelery piece.

Even if the weight and size are perfect that doesn't make it genuine. The reasons the weight and diameter are perfectly correct have already been explained with 100% certainty as well. You just choose to disregard these facts and stick to the claim that its an error while the facts say otherwise.
If you still choose not to believe the opinions here and would like to finally be completely certain, as mentioned send it to a TPG'er and in a few weeks you'll know for sure... Had you listened to that advise a while ago you'd already know.

I understand, you have your heart set on it being an error and are really hoping it is.. and I can imagine that it can be hard to find out otherwise. But that doesn't change the facts. You've been given explinations from some extremely educated, expert members who know coins inside and out.. Personally I'm not knowledgable enough in gold currency to know myself, But upon reading this whole thread and the evidence and explinations that they have given I think it's certian as to what you have.. A gold jewelry piece modeled after a US coin, with a date they wern't minted, most likely to avoid being called counterfeit...

We've all been told the saying that "nothing is impossible" and that's great advise to tell people, especially younger children so they never give up on things... But the fact of life is that some things ARE impossible.. Humans can't fly (like in the superman sense), a elephant can't mate with a mouse and give birth to a mousaflant, you cant slam a revolving door, and while there are flying fish there are no flying pigs..

I just don't understand why if you don't believe anyone here why you haven't sent it in for grading/authentication.. If you truly believe it is a real error and could be worth a fortune send it in... And then tell us all what they say, I'll happily eat my words if it comes back legit.. And be happy for you.
I'm really not trying to be rude at all, you just asked opinions and when you didn't hear what you wanted to hear you just completely disregard what people who know a lot about this say..

So the only advise I'll give, has already be said... If you don't believe anyone here and want to know for sure, send it in! And then definitely keep us posted as alot of us are waiting to hear the response..

Chicco, if you don't have that knowledge, you should send your piece in to a third-party grader--a professional who can see exactly what's going on. A Portuguese coin dealer may be able to help you. I threw "coin shops in portugal" into Google and found a dealer in Caldas da Rainha-Leiria named Sérgio W. Sousa Simões. Even if you're not in his area, you could probably find him on Google, give him a call and see if he can direct you to a colleague who's closer to you.