Dark Crystal
The Dark Crystal was a large, purple-colored crystal. Once, it had been pure and clear, and was known as the Crystal of Truth. The UrSkeks, in an attempt to purge the evil from themselves, utilized the first Great Conjunction and separated themselves into the Skeksis and the Mystics. Sometime after this, the Skeksis Emperor used his scythe to crack the Crystal, breaking off a single shard. The Crystal thereafter became corrupted as a result, and the shard found its way into the hands of Aughra.
Subsequently, the corrupted Crystal was kept by the Skeksis in the Crystal Chamber of their gloomy castle. It was suspended by unknown (and possibly magical) means above the fiery central shaft of the castle. The Skeksis drew power from it in a daily ceremony and also used light shone through it to drain the life essence of living things. A Gelfling prophecy held that a Gelfling would restore the Crystal to its original, pure state at the time of a second Great Conjunction thousands of years later.
By that time, the Skeksis (and consequently the Mystics) had dwindled in number, as had the Gelflings. It was a young male Gelfling, Jen, who obtained the shard from Aughra and stabbed it back into the Dark Crystal just as the combined light from Thra's three suns shone through the Crystal Chamber's skylight, turning it from purple to clear once more and undoing all of the corrupted Crystal's influence. It became the Crystal of Truth once again and throughout Thra, life blossomed as never before.
