The prologue of The Moonstone prepares us for both the historical background of the novel and the narrative technique. The setting of the opening and closing of the novel is India—the prologue is specifically about events on Indian soil, as well as being itself "written in India." Though the novel will follow the theft of the diamond from a household in England, the prologue reminds us that the diamond was stolen first and foremost from Indians by an Englishman. The Battle of Seringapatam is an actual historical event in the British occupation of India. The battle is significant because it reinforced the predominance of the East India Company at the time and, subsequently, British sovereignty in India throughout the nineteenth century when Wilkie Collins was writing. The Prologue is unequivocal about the unethical quality of John Herncastle's violent acts and theft of a spiritually significant object, and this can be read, by extension, as a condemnation of British treatment of occupied India.

Both the prologue and the opening chapters of the novel call attention to themselves as written documents. The Moonstone has no single narrator, and no omniscient, third-person narration that can reveal everyone's thoughts. Instead, the novel consists of over a dozen individual testimonies written by various characters involved with the diamond or the Verinder family. These characters, in turn, rely on other written documents that are often reproduced within the narrative (though some are not reproduced, as is the case with Penelope's diary). Franklin Blake, nephew to Lady Verinder, serves as the "editor" of the various testimonies and the force behind the project of taking them all down in writing. Blake suggests "we should all write the story of the Moonstone in turn—as far as our own personal experience extends and no farther." This technique of narration is well suited to the genre of detective fiction, whereby more and more information is gathered through various witnesses, and all cannot be revealed to us at once.

The opening of Betteredge's narration, with its twists and turns and constant apologies for slowness or forgetfulness, calls attention on one level to the mediation of "real" events through individual interpretation. On another level, the narration gestures toward the real difficulty of piecing together a complex novel. Yet as far as setting up a complex novel, these opening chapters—which were, along with the prologue, the first serial installment—efficiently introduce the main characters of the novel. Betteredge is a good opening narrator, since he is presented as simple enough to be believable and his servant status renders him slightly disinterested, yet with enough access to the house and institutional memory of the family to have knowledge of events that are useful to the case. Finally, Betteredge is presented as naturally skeptical or bewildered about supernatural events as we see from his wonder at the "prophetic" powers of Robinson Crusoe or his dismissal of Penelope's conclusions about the three Indians. This quality of Betteredge's allows Collins to acknowledge the exotic or unbelievable parts of the story while disarming skeptical readers.