Sonic Gems Collection is a 2005 compilation of Sega video games, primarily those in the Sonic the Hedgehog series. The emulated games span multiple genres and consoles—from the Sega Genesis to the Sega Saturn—and retain the features and errors of their initial releases with minimal edits. Player progress is rewarded with demos of other Sonic games, videos, and promotional artwork spanning the history of the Sonic franchise. While its 2002 predecessor, Sonic Mega Collection, comprises popular Sonic games, Gems Collection focuses on more obscure games, such as Sonic CD (1993) and Sonic the Fighters (1996). Other non-Sonic games are included, but some, such as the Streets of Rage trilogy, are omitted in the Western localization.

Developer Sonic Team conceived the compilation to introduce younger players to older Sonic games. One game they wished to include, SegaSonic the Hedgehog (1993), was excluded due to emulation difficulties. Sega released Gems Collection for the GameCube and PlayStation 2 in August 2005. Reviews were mixed or average; critics were divided over whether the package would satisfy players. They preferred Sonic CD and Vectorman, but found Sonic the Fighters and Sonic R mediocre, and disliked the Game Gear games. Some were disappointed by the absence of the Streets of Rage games in the International version and other Sonic games like SegaSonic the Hedgehog, Knuckles' Chaotix and Sonic the Hedgehog Pocket Adventure.

Sonic Gems Collection is a compilation of obscure video games published by Sega for various consoles, such as the Sega CD, Sega Saturn, and Game Gear. It primarily focuses on Sonic the Hedgehog games, including Sonic CD (1993), Sonic the Fighters (1996), Sonic R (1997), and six of the twelve Sonic games released for the Game Gear, with the other six having been included in the previous compilation release, Sonic Mega Collection Plus. These games encompass various genres, such as platforming, fighting, racing, pinball, and puzzle. Players can also unlock the two Vectorman games for Sega Genesis (1995 and 1996). Four additional games, Bonanza Bros. (1990) and the Streets of Rage trilogy (1991–1994), are unlockable only in the Japanese version and are not included in any international releases. Each game is mostly identical to its initial release, but some were changed; for example, Sonic R runs at a higher frame rate. Players can view scans of the original instruction manuals for each game, along with hints and cheat codes.

The compilation features an extensive museum section in which players can view content—such as promotional artwork, videos, screenshots, and remixed music—unlocked after obtaining achievements. Time-limited demos of the Genesis Sonic games and the other six Game Gear games can also be unlocked. In each demo, the player begins in the respective game's final level and can play until the time limit is met.

Sonic Gems Collection was developed by Sonic Team and published by Sega for the GameCube and PlayStation 2. According to Sonic Team director Yojiro Ogawa, the compilation (and its 2002 predecessor Sonic Mega Collection) was conceived to introduce young players to older games in the Sonic franchise. While Sonic Mega Collection focused on the original Genesis games to showcase what made the franchise a success, Sonic Gems Collection focused on games Sega considered rare and obscure. Although Sonic Team was responsible for Sonic Gems Collection's creation, they had limited involvement in the development of the games included on the compilation; for example, Sega AM2 made Sonic the Fighters, and Sonic R was primarily developed by Traveller's Tales. Most of the games included are emulated, but Sonic the Fighters is a port.

At the beginning of Gems Collection's development, Sonic Team made a list of the most wanted games for the compilation. The team considered the games they felt were high quality in graphics, gameplay, and overall nature. Sonic CD and Vectorman were considered for inclusion in Mega Collection, but were deferred to Gems Collection. Producer Yuji Naka said storage constraints prevented Sonic CD from inclusion in Mega Collection. AM3's SegaSonic the Hedgehog (1993) was omitted due to problems emulating its trackball controls. AM2 assisted in porting Sonic the Fighters, marking its first release on a home console. The Windows versions of Sonic CD and Sonic R were used in Sonic Gems Collection. Both games received visual upgrades: Sonic CD's opening sequence is presented in fullscreen and Sonic R has higher resolution textures.

During development, Sonic Team hoped that each region's version of Sonic Gems Collection would be identical in content. However, the Streets of Rage games and Bonanza Bros. had to be omitted from the Western localization, due to fears of a "Teen" rating from the Entertainment Software Rating Board (ESRB). The team also wished to include both the Japanese and North American Sonic CD soundtracks, but storage and licensing problems resulted in Japan only receiving its respective soundtrack and all other regions using the North American version. Sonic Gems Collection was announced in May 2005, and was playable at the Electronic Entertainment Expo (E3). It was released on August 11, 2005 in Japan, August 16, 2005 in North America, September 30, 2005 in Europe. In Australia, the game was released for PlayStation 2 and GameCube the following week on October 5 and October 7, respectively. The PlayStation 2 version was not released in North America. Those who ordered the game through Sega's online store Sega Direct received an exclusive Sonic-themed yo-yo.

According to Metacritic, a video game review aggregator, Sonic Gems Collection received "mixed or average" reviews. By November 22, 2005, the compilation sold 200,000 copies outside Japan. In 2006, the GameCube version was branded a Player's Choice game.