Initially, in the manga, the key is depicted to be an ordinary golden key with the crest of the Twins, a symbol similar to two I's merged, stamped on its bow. In the anime, the key is still depicted as gold but is designed more intricately. The bow of the key is sculpted with the heads of Gemi and Mini, two circular faces with two dots for eyes and boomerang-shaped mouths, one in a smile while the other one in a frown. The sides of the bow features an arm from each of the twins protruding. The blade of the key ends in a design similar to a harp.
While in possession of the key, a Celestial Spirit Mage may be able to summon the Twins Gemini by reciting the quote, "Open the Gate of the Twins! Gemini!". This summons a pair of humanoid Celestial Spirits capable of transforming into other people, granting them access to the transformed person's Magic and memories.
- ↑ Fairy Tail Manga: Chapter 165, Page 5
- ↑ Fairy Tail Anime: Episode 69
- ↑ Fairy Tail Anime: Episode 58
- ↑ Fairy Tail Manga: Chapter 143, Page 13