It costs more to produce than the market price => it can't be counterfeited.

I see your point, but if it cost more to produce than the market price then nobody would mine gold. What separates gold from most other things is its durability not it's rarity. Gold from mined hundreds of years ago is just as valuable as fresh gold so the amount of new gold entering the market each year has little impact on its supply.

By produce, I mean producing it using nuclear reactors/radioactivity from other elements, not mining.

I edited that comment, but more generally do you see a real difference between say extracting 10trillion dollars’ worth of gold from the world’s oceans from manufacturing it? With Diamonds I can see the appeal of natural gems but with gold it’s next to meaningless.

My point was that that a govt or bank can't "cheat" by leveraging it or counterfeiting it. Yes, if very large accessible reserves were found, one's savings in gold would be hurt but it would would not happen simply at the diktat of a government. The fact that you can mine it or produce isotopes does not change the fact. I did not say anything about its inherent value.