Cerra

Blue Box: The gems are in the only true box.

White box: Only one statement is true.

Black Box: The gems are in the blue box.

A: Black box

Blue box: This box's statement is both true and false.

White box: The blue box contains the gems if its statement is false.

Black box: This statement is as true as the white box's statement.

A: Blue box

Blue box: Only one box is true

White box: The black box contains the gems

Black box: The blue box contains the gems.

A: White box