Coins with abnormal colours

Hi!
I found those coins recently and I just don't know what are they. I mean, I can identify them but they don't have their original toning. The colour of the coin You see is real.



And another coin:



Regards
Kuna

https://en.numista.com/catalogue/pieces6472.html
This one looks ok

No because the original picture is bad. The original coin is "brownish" because of Bronze and mine is more "yellowish". It looks like Brass to me.
Regards
Kuna

Result of expluatation.

The second coin looks fine, alloys can very greatly. The second one looks as it is in wet conditions; remember, a coin has a long life and who knows where it's been. The first photo does not surprise me.