Amallah

Blue box: You will open this box and find it empty.

White box: A true box contains the gems.

Black box: This box and the white box are both false.

A: White box

Blue box: The second statement on the black box is false. The black box contains the gems.

White box: Every statement with the word 'blue' is false.

Black box: Both statements on the blue box are true. The blue box contains the gems.

A: Black box