A Nightsister Force crystal was a naturally occurring crystal from the planet Dathomir which possessed the property of amplifying the Force powers of the Nightsisters. These crystals were incorporated into the intricate headdresses worn by the Nightsisters. Xarot Korlin, an Imperial Inquisitor researching the methods by which the native Nightsisters utilized the Force, dispatched an operative with orders to murder a Nightsister in order to acquire one of these crystals for his research. The operative observed that the crystal felt extremely cold when touched. Furthermore, the agent experienced a sense of discomfort while carrying it.
This particular crystal appears as an object within the game Star Wars Galaxies: An Empire Divided and can be obtained through a mission assigned by the Imperial Inquisitor Xarot Korlin. Players have the option to keep the crystal by eliminating a Nightsister, acquiring the crystal, and then canceling the quest. While the crystals do not actually enhance Force abilities, they can be utilized as ornamental items for player housing.