Colin Murray Archer (b. December 7 1966 County Durham), better known as Gem (pronounced with a hard "G") after the Scottish footballer Archie Gemmill, is a musician, and currently plays rhythm guitar in British rock band Oasis having taken over from founding member Paul Arthurs in 1999. Archer began his musical career in Whirlpool , graduated to singer and guitarist status with Creation Records signing Heavy Stereo but after just one album was drafted into Oasis.

Gem is officially referred to as Oasis' rhythm guitarist, but in reality he and Noel Gallagher split many of the lead parts so that Noel can concentrate on his singing. Noel has already admitted Gem is by far the superior guitar player. Gem is also a vegetarian and a talented artist. He has a wife named Lou, a son, Joel, and a daughter named Libby. On Oasis' 5th album Heathen Chemistry Gem has his first contribution to the band, displaying his songwriting abilities in the rock song "Hung in a Bad Place". One new song of Gems - "A bell Will Ring" - was performed in Glastonbury 2004. For their upcoming 6th record in May 2005, Gem will have more songwriting credits.

Oasis Bassist Andy Bell higlights Archer's significance to Oasis saying "Oasis has completely evolved. Noel's old mates left, he's been divorced and really changed his own life around. He still has Liam but his relationship with Liam is different - It's more tempestuous. He needs a less extreme mate and Gem's it. Gem chills Noel out. And that makes Oasis a more stable ship."

Gem also took important role in making the Nine Inch Nails' latest record in middle 2004 before starting final sessions in September 2004 for Oasis' upcoming record.