Well, it's getting philosophical now. We do not have a way to experience the true nature of the coin. We can only experience an "image" [0] of the coin and we summarize all "images" of that object into knowledge.
[0] by image I do include your vision, but also hearing, feeling and other methods of perception.
I do not think there is anything very philosophical here, just the point that the claim in the post I was replying to was demonstrably false.
I am intrigued by the idea of the coin having a "true nature" that we have no way to experience; I would like to know what this elusive "true nature" is, but if we cannot experience it, I don't suppose you can tell me. Instead, I will settle for an explanation of how you know it has such a true nature.
[0] by image I do include your vision, but also hearing, feeling and other methods of perception.