The book is regarded by some as the precursor of the modern mystery novel and suspense novels. T. S. Eliot called it "the first, the longest, and the best of modern English detective novels in a genre invented by Collins and not by Poe", and by Dorothy L. Sayers as "probably the very finest detective story ever written". In "The Victorian Age in Literature" G. K. Chesterton calls it "Probably the best detective tale in the world." It was published in 1868, after Poe's mysteries "The Murders in the Rue Morgue" (1841), which introduced the famous locked-room paradigm; "The Mystery of Marie Rogêt" (1842); and "The Purloined Letter" (1845). The plot also shows some parallels with an earlier murder mystery story by the English novelist Sarah Burney, The Hermitage (1839): the return of a childhood companion, the sexual symbolism of defloration implied in the crime, and almost catatonic reactions of the heroine to it, for instance; but The Moonstone introduces in novel form, as opposed to Poe's short story form, a number of elements that were to become classic attributes of the twentieth-century detective story:
- English country house robbery
- An "inside job"
- red herrings
- A celebrated, skilled, professional investigator
- Bungling local constabulary
- Detective enquiries
- Large number of false suspects
- The "least likely suspect"
- A rudimentary "locked room" mystery
- A reconstruction of the crime
- A final twist in the plot
Franklin Blake, the gifted amateur, is an early example of the gentleman detective. The highly competent Sergeant Cuff, the London policeman called in from Scotland Yard (whom Collins based on the real-life Inspector Jonathan Whicher who solved the Constance Kent murder), is not a member of the gentry and is unable to break Rachel Verinder's reticence about what Cuff knows to be an inside job. The social difference between Collins' two detectives is nicely shown by their relationships with the Verinder family: Sergeant Cuff befriends Gabriel Betteredge, Lady Verinder's steward (chief servant), whereas Franklin Blake eventually marries Rachel, her daughter.
The Moonstone represents Collins's only complete reprisal of the popular "multi-narration" method that he had previously utilised to great effect in The Woman in White. The technique again works to Collins's credit: the sections by Gabriel Betteredge (steward to the Verinder household) and Miss Clack (a poor relative and religious crank) offer both humour and pathos through their contrast with the testimony of other narrators, at the same time as constructing and advancing the novel's plot.
One of the features that made The Moonstone such a success was the sensationalist depiction of opium addiction. Unbeknownst to his readership, Collins was writing from personal experience. In his later years, Collins grew severely addicted to laudanum and as a result suffered from paranoid delusions, the most notable being his conviction that he was constantly accompanied by a doppelganger he dubbed "Ghost Wilkie".
It was Collins's last great success, coming at the end of an extraordinarily productive period which saw four successive novels become best-sellers. After The Moonstone he wrote novels containing more overt social commentary, which did not achieve the same audience. A heavily fictionalised account of Collins' life while writing The Moonstone forms much of the plot of Dan Simmons' 2009 novel, Drood.
Although Moonstone is often seen as the first detective novel, Edgar Allan Poe's short story mysteries, The Murders in the Rue Morgue (1841) and The Purloined Letter (1845) were published before The Moonstone. Also a number of critics suggest that Charles Felix's (pseudonym for Charles Warren Adams) lesser known Notting Hill Mystery (1862–63) preceded The Moonstone by a number of years and first used techniques that would come to define the genre.