Eye of Onyx
The Eye of Onyx, an enchanted piece of SandWing Treasure, is a black sphere with wings made from molded, beaten gold, (said by Sunny to resemble Wings of Fire) and set on a chain of golden links. It is most likely made of onyx, hence its name.
Whoever holds the Eye of Onyx rules the Kingdom of Sand, as long as the current SandWing queen has died. Therefore, if Princess Blaze, Princess Blister or, Princess Burn were to have the eye they would have become queen, stopping the war, as Sunny did in The Brightest Night. Sunny had given it to her mother, Thorn, the leader of the Outclaws. Afterwards, Blister tried to steal it, resulting in her death. Since the current queen was alive and hadn't either died or given Blister the Eye, she was electrocuted and reduced to nothing but "a pile of black dust".
