Imperium Silver Crystal

The Imperium Silver Crystal (also known as the Silver Imperium Crystal, Silver Moon Crystal, Imperium Crystal, and simply Silver Crystal) is a crystal with magical powers held by members of the Moon Kingdom.

It was in the possession of Queen Serenity before the Negaverse invaded the Moon Kingdom. To stop them, Queen Serenity used the power of the crystal to imprison everyone from the Negaverse (using the attack Cosmic Moon Power). When she sent the Seven Shadows into the earth's atmosphere, the crystal was separated into seven rainbow crystals. In Sailor Moon R, it is also used when Sailor Moon transforms (saying "Moon Crystal Power")

Each of the rainbow crystals, along with the soul of one of the shadows, was kept inside a different person, until they were extracted by Zoycite (though the shadows were killed when Sailor Moon healed the carriers). Zoycite got four crystals, however the Sailor Scouts got one, and Tuxedo Mask got two. Eventually Sailor Moon was forced to hand over her crystal to Zoycite.

Zoycite challenged Tuxedo Mask (Darien) to a battle over the crystals, but had Malachite take all seven of them. However, after Tuxedo Mask was injured by Zoycite, the crystals combined into the Imperium Silver Crystal, transforming Sailor Moon into Princess Serena. She defeated Zoycite with Cosmic Moon Power. Malachite's arc revolved around him trying to find Sailor Moon and take the crystal (as it was needed to release the Negaforce), but eventually Sailor Moon defeated him with Cosmic Moon Power, killing him by reflecting his own attack back at him. Cosmic Moon Power was also used to destroy Queen Beryl (combined with the Negaforce as well) with a massive energy ball.

The Silver Crystal of the future was taken by Rini, and vanished inside her before she and the Negamoon Family traveled into the past. Though one Silver Crystal was weaker than the Dark Crystal, Rini discovered her Silver Crystal while Princess Serena was fighting Wiseman, and with both of them using two Silver Crystals, they proved to be stronger than the Dark Crystal, decimating it and destroying Wiseman. In The Promise of the Rose, the Silver Crystal took the shape of a blossoming flower. In Hearts in Ice, the Silver Crystal took the form of a large diamond.

Trivia

 * In the original promo, the Imperium Silver Crystal was known as the Empyrean Silver Crystal, and this name was used in all Bandai America Inc. merchandise including toys and cards. The name stuck on future merchandise releases until finally being corrected in 1998.
 * The Silver Crystal has also been seen written as Empirian Silver Moon Crystal by the DIC Promotional team, and Emperium Silver Crystal in YTV's online episode guides.