Collins alludes to a British colonial war crime repeatedly in the first Prologue when he discusses the "taking of Seringapatam" by the British Army. British soldiers invaded and "took" the city of Seringapatam, the capital of the region of Mysore, in 1799. Altogether, in addition to quashing the Indian forces in the area, the army stole an estimated £1,500,000 worth of treasure. This "taking" of both land and resources was considered a decisive and important victory in British colonization of India.
This allusion is important because The Moonstone was published just after a major upheaval in British administration in India. Following the First War of Indian Independence, also called the Indian Rebellion of 1857, Britain had replaced one system of subjugating India with another. The British East India company's system of monopoly rule within India was replaced in 1858 by British governmental rule of the subcontinent. Collins's sometimes stereotypical and sometimes surprisingly nuanced descriptions of Indian customs and people were taken at face value by the British public. By the 1860s, the population of Britain was growing more and more discontented with how the British government handled the expense and the military requirements of being a major colonial power.
Although it undoubtedly and repeatedly contains problematic, stereotypical, and generalizing portrayals of Indian peoples and cultures, The Moonstone is in many ways unusually critical of the British Raj for a novel of its time. British soldiers in this book are not depicted as superior to the Indian people they try to subjugate; indeed, they are portrayed by the author less positively than the native population of the country. Collins's writing also sometimes depicts the "Three Indians" as important characters, and as a posse with agency, excellent strategic thinking, and individual characteristics. The repatriation of the Moonstone itself to India at the end of the novel is also an unusual choice by a British author. Indian characters triumph in The Moonstone: the three Brahmins who come to Britain to repossess the Moonstone overcome the British opposition and succeed in achieving their goal.
Wilkie Collins makes an allusion to some of the most famous treasures of the British and Russian empires in this novel. The diamond at the center of the book is inspired by several important gems stolen from British India by Western colonizers. Collins says himself in the Preface to the 1868 edition that it's inspired by real stones. "With reference to the story of the Diamond," he tells his reader, "I have to acknowledge that it is founded, in some important particulars, on the stories of two of the royal diamonds of Europe. The magnificent stone which adorns the top of the Russian Imperial Sceptre, was once the eye of an Indian idol. The famous Koh-i-Noor is also supposed to have been one of the sacred gems of India."
The "Orlov Diamond" to which Collins refers first was set at the top of the Russian scepter while Russia still had a monarchy. It has been lost to history since the Russian revolution of 1917, but until then was one of the largest diamonds ever unearthed. The Koh-i-Noor is currently set in one of the British Royal Family's crowns and can still be viewed at the Tower of London today. Many people who read The Moonstone when it was first published might actually have seen the Koh-i-noor in real life, as the stone was placed on display in London in 1851, as one of the spoils of Empire. It appeared in an enormous exhibit put on by the British Royal Family, called the "Great Exhibition."
These stones are enormous, and their relationship to colonizing nations is as clear as their sparkling bodies. The Moonstone diamond would have been made easier for Collins's Victorian public to imagine, given the author's allusions to real, famously colossal and opulent stones. Both of these real gems were taken from India and paraded as symbols of the power of the Russian and British empires, and both symbolize the dubious legacy of theft from the subcontinent.
Collins also specifically mentions the misfortune that was fabled to befall anyone who stole these gems. He says in the same Preface that the Koh-i-Noor was supposed to "have been the subject of a prediction, which prophesied certain misfortune to the persons who should divert it from its ancient uses." This inspired Collins to place the same "curse" on the imaginary Moonstone, which in the novel is also said to blight anyone who steals it. Collins knew both the real histories of colonial gems and the stories that surrounded them, incorporating them into The Moonstone to add to its realism and its social relevance.
Collins makes several allusions to another important English novel in The Moonstone: Mr. Betteredge is obsessed with Robinson Crusoe. He bases his whole philosophy of life on it and relies on it in times of need, as he says in Chapter 1 of the First Period:
such a book as Robinson Crusoe never was written, and never will be written again. I have tried that book for years [...] and I have found it my friend in need in all the necessities of this mortal life. When my spirits are bad – Robinson Crusoe. When I want advice – Robinson Crusoe. In past times, when my wife plagued me; in present times, when I have had a drop too much – Robinson Crusoe. I have worn out six stout Robinson Crusoes with hard work in my service.
Betteredge is such a huge fan of this book that he has "worn out" six editions of it by reading it so much. This is certainly an intense level of devotion, but Robinson Crusoe was a very influential novel. Written in 1719 by Daniel Defoe, it's sometimes called the first English novel, and has remained an important work in the British literary canon since its publication. Like The Moonstone, it's a story which involves places far from Britain. Also like The Moonstone, it's a rollicking adventure full of dramatic twists, stereotypical depictions of foreigners, and has a family drama at the center of the narrative. It is also a book which engages with ideas related to colonialism and "exploration," and which contains moralizing language on Christian behavior.
Early in the novel Collins alludes to a real-life criminal case, the "Road Hill House Murder" of 1860. The allusion appears when the "stained nightgown" comes into play as a clue in the Moonstone investigation. When Betteredge realizes the alleged connection that Sergeant Cuff makes between the nightgown and the theft in Period 1 Chapter 22, he is absolutely stunned by its implications:
If he had thrown a bucket of cold water over me, I doubt if I could have felt it much more unpleasantly than I felt those words. Miss Rachel’s assertion of her innocence had left Rosanna’s conduct – the making the new nightgown, the hiding the smeared nightgown, and all the rest of it – entirely without explanation. And this had never occurred to me, till Sergeant Cuff forced it on my mind all in a moment!
Cuff's revelation recalls the very public and famous case of the Road Hill House murder, which Collins's audience would very likely have been familiar with. The suspects in both this real crime and Collins's fictional one were initially both young Englishwomen: Rosanna Spearman in The Moonstone and a person named Constance Kent in the actual case. Solving the case and convicting Kent of murdering a four-year-old child in 1860 hinged on the presiding detective finding a stained nightgown.
In The Moonstone, Rosanna hides away Francis Blake's nightgown, which is dirtied with paint from the freshly-decorated door of Rachel's bedroom. Blake's name embroidered in the nightgown is a shocking twist, but might have been more predictable for a Victorian reader because of the similarity to the Road Hill case. Blake "discovers" he is in fact the thief when he finds the nightgown through instructions in Rosanna's suicide note: inside it is embroidered, as he horridly recounts, "MY OWN NAME."
Miss Clack uses a hyperbolic biblical allusion in Narrative 1, Chapter 2. This allusion functions as a metaphor to describe some visitors arriving to accompany Rachel Verinder to a flower show. In this section Clack tells the reader that:
[...] a thundering knock at the street door startled us all. I looked through the Window, and saw the World, the Flesh, and the Devil waiting before the house – as typified in a carriage and horses, a powdered footman, and three of the most audaciously dressed women I ever beheld in my life
Drusilla Clack thinks Rachel is arrogant, badly behaved, and un-Christian, and is always trying to improve her behavior by forcing fundamentalist religious pamphlets on her. It's unsurprising, given this, that Clack believes Rachel's friends are "the most audaciously dressed women" she's ever seen. The situation she is describing—people arriving to pick up a friend in a carriage—is actually quite normal, but through Clack's hyperbolic voice, it becomes an occasion of bombastic significance.
Clack refers to the girls in the carriage as "the World, the Flesh, and the Devil waiting before the house." This trio of things is an allusion by the author to the writing of Thomas Aquinas, a 13th century Italian theologian. Aquinas described the three things Clack references here as the "implacable enemies of the soul." Aquinas is a canonical Christian figure, and this reference would have been a familiar one to Collins's largely Christian British audience.
Of course, the idea that some flashily-dressed girls in a carriage could be the embodiments of the "enemies of the soul" is obviously farcically overblown. Nevertheless, Miss Clack sees opportunities for sermonizing everywhere, especially when they involve criticizing Rachel. This is another instance in The Moonstone where the insatiable Miss Clack makes a ludicrously exaggerated and negative religious reference to align something quite ordinary, even pleasant, with something very bad indeed.
In Chapter 10 of the Third Narrative, Collins alludes to Confessions of an English Opium-Eater, a memoir by Thomas De Quincey published in 1821. Ezra Jennings gives the book to Blake to explain the power of opium to him:
‘There,’ he said, ‘are the far-famed Confessions of an English Opium Eater! Take the book away with you, and read it. [...] So much for the capacity of a man to occupy himself actively, and to move about from place to place under the influence of opium.’
This "far-famed" book, which shocked the nation of Britain upon its publication, became wildly popular in the Victorian period. It went through several editions and provoked public outcry because of its frank account of drug use. Confessions of an English Opium-Eater was one of the first addiction memoirs ever published. It detailed the dependency that the author developed to laudanum, an addictive drug in the opioid family made by dissolving ground opium poppy seeds in alcohol. It was widely available without a prescription during the 19th century, and was taken for a huge variety of purposes; from controlling "hysteria" in women, to pain relief, to promoting creativity in writers and artists. Collins himself wrote The Moonstone under the influence of the drug.
By alluding to this book, Collins foreshadows the eventual revelation of how the Moonstone was really stolen. Confessions of an English Opium Eater contains many references to doing things one doesn't remember while on opium, and to dreaming new drug-induced realities. When Jennings recommends the book to Blake, he gives Blake a source of insight into understanding how he could have stolen the gem. Blake thinks opium just puts you to sleep; Jennings explains that its effects go far beyond this, potentially enabling Blake to have committed the crime without knowing it.
At a key point in The Moonstone, Collins alludes to contemporary Victorian scientific ideas about "constitutions." In this context, that word refers to people's personalities and general sense of being, particularly as they were associated with gender roles. In Chapter 10 of the Third Narrative, Ezra Jennings describes himself as having a "female" personality to Franklin Blake:
'I laid the poor fellow’s wasted hand back on the bed, and burst out crying. An hysterical relief, Mr Blake – nothing more! Physiology says, and says truly, that some men are born with female constitutions – and I am one of them!’
He made that bitterly professional apology for his tears, speaking quietly and unaffectedly, as he had spoken throughout.
Jennings implies that his "hysterical relief" is a gendered trait, which renders his "constitution" insufficiently masculine. This statement contributes to the stereotypical Victorian image of male people from British colonies in the global South and East. Men from these areas are often portrayed as being feminine and ethically feeble. Ezra Jennings, a student of medicine, believes that "physiology" indicates that he has a "female" constitution, and that it's a serious failing of character. Weakness, smallness, and emotional intensity are all linked to the feminine in this novel, as strength, size, and stoicism are described as masculine in characters like Mr. Bruff and Colonel Herncastle.
The idea of "hysteria" which Jennings mentions here is also linked to Victorian ideas of femininity. "Hysteria" was a pseudoscientific diagnosis of mental illness applied to many women before the late 20th century. Its name comes from the Greek word for "womb" and was thought to be the cause of erratic and headstrong behavior in women and girls. As Jennings refers to himself as "hysterical" here, he's also making a subtle reference to his opium addiction, in two ways. First, opium was an extremely common "cure" for hysteria as it was diagnosed in the 19th century, as it was a powerful sedative. Jennings is addicted to a "medicine" very often used by emotional women. Second, his addiction to opium is framed by Collins as being caused by personal weakness. It is not "masculine" to give into vices, and so Jennings's "female constitution" is also linked to his use of drugs.