Gems (ジュエル, Jueru, or "Jewels") in the Pokémon world are special type-enhancing hold items introduced in Pokémon Black Version and Pokémon White Version. Each Gem used to increase the specified damaging attack of the same type by half after it's been used for one time in Generation V games, but now, they can increase the attack by 30% as of Pokémon X and Pokémon Y.
Summary(besides raising the move)
Notes and Locations
(むしのジュエル, Mushi no Jueru,
or "Insect Jewel")
This gem has an insect-like essense.
The Bug Gem can be found inside the Pinwheel forest in Unova.
(あくのジュエル, Aku no Jueru
or "Evil Jewel")
A gem with an essense of darkness.
The Dark Gem can be found in Unova Route 9.
(ドラゴンジュエル, Doragon Jueru,
or "Dragon Jewel")
A draconic essence is infused with this gem.
The Dragon Gem can be found in the Mistralton Cave in Unova.
(でんきのジュエル, Denki no Jueru
or "Electric Jewel")
This gem has an essence of electricity.
The Electric Gem can be found in the Chargestone Cave in Unova.
(フェアリージュエル, Fearī Jueru
or "Fairy Jewel")
A gem with an aromatic essence.
The Fairy Gem exists in the codings for Pokémon X and Pokémon Y, and may be given out in a future event for Kalos region players.
(かくとうジュエル, Kakutō Jueru
or "Fight Jewel")
A gem with an essence of combat.
The Fighting Gem can be found in the Pinwheel Forest in Unova.
(ほのおのジュエル, Honō no Jueru,
or "Flame Jewel")
An essence of fire resides in this gem.
The Fire Gem can be found in the Reversal Mountain in Unova, but only if the player is playing Pokémon White Version 2.
(ひこうのジュエル, Hikō no Jueru
or "Flying Jewel")
This Gem has an airy essence.
The Flying Gem can be found in Mistralton City in Unova.
(ゴーストジュエル, Gōsuto Jueru
or "Ghost Jewel")
A spectral essence inhabits this gem.
The Ghost Gem can be found in the Celetial Tower in Unova.
(くさのジュエル, Kusa no Jueru
or "Grass Jewel")
This gem has a natural essence.
The Grass Gem can be found in many of Unova's dust clouds.
(じめんのジュエル, Zomen no Jueru
or "Earth Jewel")
An essence of land is this gem's fragrence.
The Ground Gem can be found in Dessert Resort in Unova.
(こおりのジュエル, Kōri no Jueru
or "Ice Jewel")
Chilling ice is this gem's essence.
The Ice Gem can be found in the Giant Chasm in Unova.
(ノーマルジュエル, Nōmaru Jueru
or "Normal Jewel")
This gem has an ordinary essence.
The Normal Gem can be found in Unova's Victory Road on the way to the Pokémon League.
(どくのジュエル, Doku no Jueru
or "Poison Jewel")
This gem has a toxic essence.
The Poison Gem can be found in the sewers of Castelia City in Unova.
(エスパージュエル, Esupā Jueru
or "Esper Jewel")
This gem is infused with the essence of mind.
The Psychic Gem can be found in many of Unova's dust clouds.
(いわのジュエル, Iwa no Jueru
or "Rock Jewel")
A gem with a rocky essence.
The Rock Gem can be found in the Relic Passage in Unova.
(はがねのジュエル, Hagane no Jueru
or "Steel Jewel")
A gem with an essence of steel.
The Steel Gem can be found in Clay Road in Unova.
(みずのジュエル, Mizu no Jueru
or "Water Jewel")
A gem infused with an essence of water.
The Water Gem can be found in the Reversal Mountain in Unova, but only if the player is playing Pokémon Black Version 2.