The Moonstone is a novel packed with situational irony, particularly surrounding the theft and discovery of the diamond from which it takes its title. Collins's narrative is full of foreshadowing, which is often subverted by situationally ironic twists and turns. This contributes to its effectiveness as a detective novel, as it keeps the reader guessing throughout. The irony is a key part of the novel's mystery plot, as it relies on mischance and unexpected happenings to move forward. Getting to the facts takes a long time. Notably, the section of the novel entitled "The Discovery of the Truth" only comes after two other large sections, and it takes eight chapters to resolve itself.
It seems obvious at the beginning of the book who has stolen the Moonstone from Rachel Verinder's bedroom, but that conclusion is quickly proven to be a red herring. Characters like Rosanna Spearman appear to the reader to have the means, motive, and action to be the thieves, but are then revealed to have actually been noble and self-sacrificing. Throughout the novel, Rosanna expresses fear and loathing of the murky and uncanny depths of the Shivering Sand, where things go to be forgotten. She is desperate to be noticed by Blake and fears being overlooked or forgotten about by him more than anything else. This makes it situationally ironic that Rosanna dies deliberately (and unexpectedly for the reader), doing the thing she fears most, "losing" herself to the quicksand. Further, it's only when Blake goes to the Sand and finds her confession that he really "notices" her, even though she's long lost under what she previously called its "horrible," "sucking" surface.
After many more ironically plausible misdirections by Collins, the novel eventually reveals its crowning irony. In a book full of deliberate crime and false accusation, it transpires that the person who actually stole the Moonstone from Rachel's room didn't even know he was doing it at the time. This situationally ironic twist is compounded by the fact that Godfrey Ablewhite—whom Rachel agreed to marry because she believed Franklin Blake was the thief—was actually himself the perpetrator. There's another ironic factor at play here, too: Blake "stole" the Moonstone in order to stop it from being stolen in the first place. Collins's plots are densely interwoven, relying heavily on these moments of situational irony to provoke emotion and keep the plot moving apace.
Another one of many examples of situational irony is the case of the Three Indians, men who have been tasked with finding and retrieving the Moonstone from its captors. These characters are framed as being possible, if not very likely, perpetrators of the theft in the beginning of the novel. However, Collins later makes it clear that the diamond was actually stolen first from their religious sect. The very fact of the diamond's abduction from India and its possession by Herncastle, an Englishman, is an ironic nod to the theft of Indian resources from British colonies. The Three Indians don't steal the Moonstone from Rachel, but it was originally stolen from them.
The darkness of the sensory language surrounding the Shivering Sand in Period 1 Chapter 4 is a literal version of the gloomy mass of contradictory facts, dark truths, and hidden evidence in The Moonstone. Rosanna uses hyperbolic language and provocative alliteration to describe the Sand. Her intense descriptions of it also foreshadows her own death within its depths. When Rosanna and Betteredge stand looking over the Sand together in Chapter 4, Betteredge says:
I looked where she pointed. The tide was on the turn, and the horrid sand began to shiver. The broad brown face of it heaved slowly, and then dimpled and quivered all over. ‘Do you know what it looks like to me?’ says Rosanna, catching me by the shoulder again. ‘It looks as if it had hundreds of suffocating people under it – all struggling to get to the surface, and all sinking lower and lower in the dreadful deeps! Throw a stone in, Mr Betteredge! Throw a stone in, and let’s see the sand suck it down!’
In this passage, Rosanna uses the diction of suffering and suffocation to give the reader a bold visual image of her fear of the Sand. She imagines it to be full of "hundreds of suffocating people" below the surface, and although this is hyperbolic, the quicksand itself does eventually prove to contain "suffering." It hides evidence from the people investigating the theft of the Moonstone, and it is associated with secrets, pain, and strife by every narrator.
When people describe the Sand, as Rosanna does here, it is linked to the visual language of obscurity and loss: it has "dreadful deeps" like grief and is "horrible" to look at as it shivers like a person in terror. The language of pointless struggle in Rosanna's descriptions also provokes a sense of hopelessness and despair for the reader, as she describes people "sinking lower and lower" into the muck. The alliteration of "Throw a stone in, and let’s see the sand suck it down!" also provides the reader with auditory imagery: the sucking "s" sounds in this phrase echo the plop and sink of a stone into the quicksand. All of this obsessive, gloomy talk foreshadows the later point at which Rosanna drowns herself in the Shivering Sand. She follows the arc of the stone that is "thrown in" and is also "sucked" down, never to be seen again.
A last link between Rosanna and the dark sensory language surrounding the Shivering Sand is made by Franklin Blake at the end of this chapter. As he "closes" his discussion of her suicide note, he describes the next stage of his story as his "toilsome journey from the darkness to the light." In Chapter 8 of his Third Narrative, he resolves to "force his way through all obstacles, from the darkness to the light" with the help of Sergeant Cuff's detective work.
In Chapter 5 of the First Period, the sinister Colonel Herncastle is described by the manservant Betteredge through a series of visual and auditory images. These foreshadow his sinister motives:
I expected him to break out, even at that polite way of putting it. To my surprise he did nothing of the sort; he alarmed me by taking the thing with an unnatural quiet. His eyes, of a glittering bright grey, just settled on me for a moment; and he laughed, not out of himself, like other people, but into himself, in a soft, chuckling, horridly mischievous way.
In this passage, Herncastle's quiet, his "glittering," and his "bright" and "grey" eyes suggest that his body has taken on some diamond-like qualities. He has become infected with the visual language of the Moonstone diamond, which Collins repeatedly describes using this same diction.
When Herncastle creepily laughs "into himself," this uncanny auditory imagery actually suggests a visual image as well. Diamonds have a quality called "total internal reflection," meaning that they sparkle because all the facets cut into them make light reflect within the stone. In his "horridly mischievous way," Herncastle's laughter only reflects "into himself" like cut diamonds do with light.
Later in the novel Collins reveals that Herncastle has even more diamond-like qualities: after coming into possession of the Moonstone, Herncastle begins to live his life concealed underground, like a diamond before it's dug out. All this imagery foreshadows his evil deeds, giving the reader an impression of his abhorrent personality even at this early stage. It also foreshadows the mysterious power the Moonstone seems to hold over people, as possessing it so proudly affects Herncastle.
In Chapter 4 of Narrative 3, Collins juxtaposes the visual imagery of natural beauty with the bleak emotional landscape of the horrified Mr. Blake. This contrast foreshadows the unpleasantness of the investigations into the Moonstone's theft, while Blake believes himself to be responsible. After Blake realizes he's actually the diamond thief, having read Rosanna's letter, he stands on the shore of the Shivering Sand and notices that:
The sunlight poured its unclouded beauty on every object that I could see. The exquisite freshness of the air made the mere act of living and breathing a luxury. Even the lonely little bay welcomed the morning with a show of cheerfulness; and the bared wet surface of the quicksand itself, glittering with a golden brightness, hid the horror of its false brown face under a passing smile. It was the finest day I had seen since my return to England.
In this passage, the sensory language of "exquisite freshness" and beauty contrasts with the stale and secondhand news of the crime Blake has committed. Blake does not remember stealing the Moonstone, and it seems particularly cruel that when he discovers this shocking truth, the world around him responds by bursting into life with "a show of cheerfulness" and "golden brightness." Even the Shivering Sand (usually a site of horror and unease in this novel) has a "passing smile" and is "glittering" here. Collins uses these contrasting images to make the confusion and obscurity surrounding the startling tidings in Rosanna's letter seem even more miserable than they would otherwise.
The use of the word "glittering" is also an instance of foreshadowing as it appears in this passage. This word comes up several times in the novel: it refers to the evil Colonel Herncastle's eyes (which "glitter" with malice), the sparkling Moonstone diamond itself, and the "glitter" in the eyes of people who've taken opium. Through this word, Blake's unremembered crime is linked to all three of these things, and to the Shivering Sand itself as it "glitters" in the sun.
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.
