Hiridiu crystals possessed the special ability to amplify communication signals simply by being nearby. Because of this unique feature, they were widely used in numerous communication systems throughout the era of the Old Republic. The Alliance to Restore the Republic also took advantage of this characteristic, building their clandestine Outer Rim Communications Center close to a hiridiu deposit located on the planet of Generis.
Hiridiu crystals were a type of crystal that appeared light blue-colored. They had the distinctive characteristic of boosting the power of communications signals when in close proximity. As a result, these crystals saw extensive use in many communication systems during the Galactic Republic period. By the time of the New Republic, modern communications technology could have its signals enhanced by up to 30% through the use of these crystals.
A significant accumulation of hiridiu crystals was situated at the southern pole of the planet Generis, which was located in the Atrivis sector of the Outer Rim Territories. During the Clone Wars, which was a conflict between the Galactic Republic and the Confederacy of Independent Systems, hiridiu crystals were incorporated into the construction of various technological devices. The Alliance to Restore the Republic exploited this natural deposit by establishing their covert Outer Rim Communications Center in proximity to it, under the operational control of the Atrivis Communications Group. This base remained under the control of the Alliance's successor government, the New Republic, until the Imperial resurgence led by Grand Admiral Thrawn. During the Fall of Generis, Imperial forces seized this facility, and the loss of this uniquely effective communications hub was a serious setback for the New Republic.
Eric S. Trautmann originated the concept of hiridiu crystals for The Last Command Sourcebook (1994) published by West End Games. This publication provided roleplaying game statistics related to Timothy Zahn's novel, The Last Command. This data was subsequently republished in The Thrawn Trilogy Sourcebook, which compiled the three sourcebooks produced to support the Thrawn Trilogy. Prior mentions of crystal-enhanced communications systems within Star Wars canon appeared in Han Solo and the Lost Legacy, which detailed the use of mytag crystalline vertices in ancient subspace communications. In 2013, hiridiu crystals were integrated as a common component for crafting in Star Wars: Clone Wars Adventures, an MMORPG developed by Sony Online Entertainment.