A single shade but a spectrum of meanings.
Every director has their color. Scorsese likes red, Wes Anderson likes yellow, the Coens have a penchant for green, and Tony Scott never met a filter he didn’t like. For Michael Mann, legendary director of Heat, The Insider, Manhunter, Miami Vice, and Collateral, the color is blue, and over the course of his filmography he has used it to represent life, wisdom, loyalty, fidelity, emotional isolation, stoicism, secrecy, stealth, intelligence, and both peace of mind and deliberative pensiveness.
In the following supercut from Ashley Perry, the various shades of blue in the films of Michael Mann have been collected and arranged to reveal the multifarious ways in which the director puts them to use. It also serves as proof that while some directors use color exclusively for style, and others exclusively for substance, Mann is one of the best at using color for both.