There is something red in which I have marked with yellow circle. It is comlicated to see with pictures than in hand, but i have marked it with yellow circle: Is the red thing a natural patina, or is it a chemical reaction caused due to cleaning of the coin/weight? OBS: I have NOT cleaned it. Thanks for any help you can provide.
I read somewhere sometimes slight lead in a bronze admixture creates red spots it happens in Ptolemaic coins quite often as well, I dont know if its accurate but that is what I remember -Mx
Those kind of splotches are often indicative of the coin formerly (or still) having had bronze disease. I have cured a few and that is what the scarring looks like. Here's a couple examples:
Aren’t they copper oxides that are caused when the coin is buried with silver in a moist environment? At least that’s what I read regarding Ptolemaic bronzes.