Ashe: With that much nethicite in one's grasp... Fran: You could destroy all of Ivalice, if you wished it.

The Great Crystal is a location in the land of Ivalice in Final Fantasy XII. It is a large crystal located in the deepest reaches of the Giruvegan.

The core of the crystal is a great orb of magicite, constantly spewing Mist. The party speculates that it might be nethicite. While its purpose is never revealed, the Great Crystal could be the Occuria's deposit of nethicite, or perhaps the source of magicite and Mist. Whatever the case, it acts as a deadly gateway to the Occurian dwelling, filled with powerful monsters and a twisting maze. Also sealed within are the fearsome prisoners, the Espers Ultima and Shemhazai.

Not actually located on the world map, the Great Crystal is found in the Ancient City of Giruvegan. The player has to walk down to the deepest reaches of the Gate of Fire and find a waystone, which grants access to the area. The Great Crystal links the Gate of Fire at Giruvegan with the floating Gate of Wind and is the only way the Occuria and Shemhazai can be accessed.

The names of each the areas resemble Sanskrit, but are actually contractions and bastardizations of English words and some scientific terms, which help to indicate where the player is.

The original version and the Zodiac versions have different treasures. In the original, equipping the Diamond Armlet or not determines what the player gets, making it easy to miss something valuable, whereas the Zodiac versions are more forgiving. The equipment and ability treasures can only be claimed once, bar the Gendarme. The basic item received from chests is also changed from Knot of Rust to various versions of the Meteorite item.