Sunstone Crystal is a type of crystal first developed and used on the planet Krypton, both as a building material and as a form of computer system.
Similar in nature to organic lifeforms, a sunstone crystal can be "shaped" to serve specific purposes. Some, when activated, can duplicate their mass; forming structures such as buildings or vehicles. Others shape themselves into hive-like nests to act as computer systems. While others again can serve as small communicative devices or tools and instruments.
Upon their discovery on Earth by Lex Luthor, who had found a Kryptonian Sunstone Warship and had attempted to destroy Metropolis with it, Superman disassembled the ship and inadvertently created a new Fortress of Solitude with one crystal.
Keeping the remaining crystals within the fortress, Superman continues to study their natures while determining how their use may benefit Earth and human-kind.
- The entire structure of the Fortress of Solitude is made up of sunstone crystals. During the Fortress of Solitude raids, Brainiac assimilated the sunstones of the Fortress to fortify his armies.
- The Kryptonian Medico, Sunstone Edge, Kryptonian Commander and Sunstone Bulwark Iconic Battle Suits were all created and infused with Sunstone Crystal technology.
- The Krypton: House of El's security system is comprised entirely of Sunstone Crystals.
- Several incarnations of the Fortress of Solitude are made mainly from sunstone crystals, or otherwise incorporate them into its design.
- Supergirl possesses sunstone crystals within her body which were surgically embedded by her father as a weapon against Phantom Zone "ghosts".
- The lenses of Clark Kent's glasses are made out of the Sunstone Crystals from his space ship. They were initially given to Clark by his mother to keep his heat vision in check during high school.