Rainbow Crystals

The Seven Rainbow Crystals are a set of items from Pretty Guardian Sailor Moon that were featured in the Knights of the Multiverse Mini-Series. These seven crystals are actually a part of the legendary Silver Crystal, but were split apart and flung across the Multiverse when the Black Moon Clan attacked Crystal Tokyo, and the Knights had to find them and reform the Crystal to defeat the Heralds of Unicron. As their name implies, each one has a different color of the traditional seven-color spectrum.

Pre-Series
The Silver Crystal has actually split into the Rainbow Crystals before the events of the series: During the Silver Millennium, the Dark Kingdom launched an attack against the Moon Kingdom, ruled by Queen Serenity. The queen managed to trap the Dark Kingdom's greatest warriors, the Seven Great Youma, inside the Silver Crystal, which then fragmented into seven pieces. The Crystals were sent to Earth along with Princess Serenity and her court, where the Seven Great Youma were reincarnated inside of normal human beings (and in one case, a cat). The carriers had no knowledge of the Rainbow Crystals inside of them, although in some this manifested as special abilities, such as telekinesis or other psychic powers. While the youma were sealed within the Rainbow Crystals, they were unable to exert their evil influence. Once the crystals were removed from the carriers, however, they reverted back to their Youma forms.

In the modern day (or, at least the modern day of the Silver Millenium timeline) and sought to locate the seven crystals in order to re-form the Silver Crystal and fully revive their empress, Queen Metalia. To do this, they used the Black Crystal, which could detect and then later remove the Rainbow Crystals from their carriers. During the next seven episodes, a massive search ensued. Zoisite was able to locate each of the Rainbow Crystals and extract them, causing the carriers to revert to their Great Youma form. The Sailor Guardians attempted to stop them but were usually attacked by the youma. Rather than killing them though, Sailor Moon used her Moon Healing Escalation attack to seal the Youma within their carriers once again. the Dark Kingdom managed to collect all seven of the Rainbow Crystals. When Tuxedo Mask was injured while attempting to recover them, Sailor Moon began to cry, and the crystals magically aligned with her. The seven crystals then combined with her tear, and the Silver Crystal was reformed.

Abilities
Although they are extremely powerful when united as the Silver Crystal, they lose all their powers when separated. However, they are all able to detect each other's presence.