<P> "Diamonds Are a Girl's Best Friend" is a jazz song introduced by Carol Channing in the original Broadway production of Gentlemen Prefer Blondes (1949), which was written by Jule Styne and Leo Robin . It was based on a novel by Anita Loos . </P> <P> The song is perhaps most famously performed by Marilyn Monroe in the 1953 film Gentlemen Prefer Blondes . Monroe's character, Lorelei Lee, has been followed on a Transatlantic ocean liner by a detective hired by her fiancé's father, who wants assurance that she is not marrying purely for money . He is informed of compromising pictures taken with a British diamond mine owner and cancels her letter of credit before she arrives in France, requiring her to work in a nightclub to survive . Her fiancé arrives at the cabaret to see her perform this song, about exploiting men for riches . Diamonds are an element in another story line in the film, in which Lorelei is given a diamond tiara by the mine owner, in gratitude for her recovering the photographs . In a later scene, Jane Russell, who played opposite Monroe, sang "Diamonds Are a Girl's Best Friend" in court, while pretending to be Lorelei . </P> <P> Most of the song in the film is Monroe's own voice but she needed help in two phrases--"These rocks don't lose their shape, diamonds are a girl's best friend", and at the beginning with a series of high - pitched "no's", all of which were dubbed in by the soprano Marni Nixon . </P>

Who coined the phrase diamonds are a girl's best friend