Guess they opted for fool. Huh.

I could add you if you aren't just going to phish me and claim to have accidentally reported my account despite that not being realistically a worry for literally anyone. You want to double down, or look like a fool?

You can add me? I'd like to ask a question about games.

TL;DR: The phrasing on the third box renders this puzzle a guessing game in this case, and hopefully was fixed before the full release of the game; also, I'm a logic nerd.

As far as the other two boxes and why the third box must be false in this set of statements:
- If the third box is true, then both first and second box contain gems, which would break the rules of the puzzle, and thus is impossible.
- The other two boxes are completely unimportant in truth values, as the boxes "claim" to be true is what matters for the third. As far as their truth values go, they're beside the point, and are entirely ambiguous. "This statement is false" is a paradox as it claims falsehood, but a statement claiming truth is not a paradox -- if "This statement is true" is true, then it's self-evident, and if it is false, then given it says it's true, it is inaccurate, and thus false, which is clear and logically sound.

I love this puzzle design and style, but also, this is a broken set of three statements for this puzzle design, and should be removed or fixed. You could fix it by changing the third statement to say "A box that claims to be true contains gems." Then, if it is true, then you don't know which box the gems are in, but if it's false, then you know exactly which box it's in. This makes the other boxes way more clearly completely unimportant, but also, they already were , so you haven't actually changed anything there.

Looking at the below situations, you see the problem, now. The gems could be in any box, and the statement would still be false -- the statement does not tell you which box they're in. This comes from the logic of that statement, it's a plural, so there's some omitted detail that is important -- it can be expanded to say "All boxes that claim to be true contain gems." The inversion of that, then, is not "All boxes that claim to be true do not contain gems." The inversion is "Not all boxes that claim to be true contain gems." In which case, the gems could be in either box claiming to be true, or in neither of them.

The issue resides in the third statement. Let's consider situations before I point out the logical misstep here, so people don't get confused.

Situation 1: Box 1 contains gems. In this case, Box 2, that claims to be true, does not contain gems, so the statement "Boxes that claim to be true contain gems" is false -- only 1 box that claims to be true contains gems, so "Boxes" do not.
Situation 2: Box 2 contains gems. In this case, Box 1, that claims to be true, does not contain gems, so the statement "Boxes that claim to be true contain gems" is false -- only 1 box that claims to be true contains gems, so "Boxes" do not.
Situation 3: Box 3 contains gems. In this case, no box that claims to be true contains gems, so the statement "Boxes that claim to be true contain gems" is false.

Commenting due to limited character length. The statements on the boxes read "The statement on this box is true." "The statement on this box is true." and "Boxes that claim to be true contain gems."