While the 2014 film Gone Girl is about the darker intentions hidden beneath the surface of the supposedly unassuming couple Nick and Amy (Played by Ben Affleck and Rosamund Pike, respectively), one aspect that was essential to creating this deception was the fashion of the characters. This was accomplished through the lead costume designer, Trish Summerville, who worked with director David Fincher on his previous film, 2011's The Girl with the Dragon Tattoo. In an interview with InStyle magazine at the time of the film's release, Summerville discussed that she wanted Nick and Amy's clothing to look contemporary due to the films present day setting, yet understated and simple as to illustrate the idea that Nick and Amy are a regular and unassuming couple. She also wanted the clothes to look like everyday life as if they ordered them online or bought them at the mall though figuring out what "everyday life" would look like for Nick and Amy was one of her biggest challenges.
Ultimately, Summerville concluded that Amy carried a self proclaimed "cool girl" status, her costumes directly meant to reflect the traditionally chic yet girl-next-door attitude. However, she felt Amy's pieces can be seen as more timeless over high fashion and trendy as Amy is just "kind of not that girl". This is exemplified through Amy's jewelry as she wears a Rose Gold Cartier Love bracelet as well as a necklace containing a floating 'A' to show how Amy holds onto keepsakes from the past. As for Nick Dunne, Summerville felt he also is more simple in the way he presents himself, thus dressed him in simple yet well-fitting suits and found that designer suits fit best due to actor Affleck's larger build. In the film, Nick can be seen wearing suits from Dolce & Gabbana, as well as Prada shirts. One of the most important pieces in the film is the shirt (a blue button-up designed by Steven Alan, paired with J brand jeans) that Nick puts on when he comes home to find his wife missing because he does not take this shirt off for the days following.
On a final note, when Amy and Nick move to Missouri, Summerville made minor changes to Amy's wardrobe in order to signify change which is why she wears more muted colors, more jeans, and less high-heels. If this movie fact felt boring to you in discussing the mundane element of costume design...congrats...you got the point of this. Stay tuned!