The Uraj and Khalis Crystals were ancient and sacred Khaydarin Crystals created by the Xel'naga for the fledgeling Protoss. These crystals had played major roles in Protoss history, and had ultimately saved their race upon the Dark Templar homeworld of Shakuras.
The Uraj Crystal had been infused with Khalai energies due to being entrusted to the Akilae Tribe's Templar warriors, and had taken on a deep purple hue. The Khalis, who had been entrusted to the rebellious Sargas Tribe, was infused with Dark Templar energies and had taken on a sky blue color. Their combined powers allowed Artanis and Zeratul to activate a Xel'naga Temple upon Shakuras which had scoured the planet of all things Zerg.