Dickie's Rings (Symbol)
For both readers and characters, Dickie's rings are a symbol of his identity. Tom takes Dickie's rings after killing him, knowing that he cannot impersonate him without the rings, and also knowing that his act of violence will not feel real or meaningful if he cannot possess this symbol of Dickie's individuality. Indeed, Tom holds on to Dickie's rings even when he knows that they might end up serving as evidence of his guilt. This choice is not wholly rational, but is rooted in the symbolic power of the rings, which make Tom feel empowered to impersonate Dickie. When Marge finds the rings in Tom's house, though, she does not assume that he is guilty. Rather, because of the symbolic power of the rings, Marge assumes that Dickie has killed himself, since she believes that he would not have parted from his rings while alive.
Paris (Symbol)
For Tom, Paris is a symbol of the lifestyle he longs for. The city occupies an outsized place in his mind, and he feels personally wounded when Dickie turns down the opportunity to travel there with him, since he views traveling to Paris as a culmination that would cement and elevate their friendship. Tom associates Paris with everything he desires: wealth, exclusivity, culture, and excitement. When he does get to visit the city, he does not enjoy its culture or beauty so much as he enjoys the feeling of conquering a prized new territory. Therefore he focuses on getting invited to parties, feeling that being accepted by the Paris social scene represents the greatest possible achievement.
Mirrors (Motif)
Most of the time, Tom is so disconnected from his negative emotions (and so determined to stem them by any means necessary) that he can't actually discern what he feels like. Instead, Tom, who is keenly observant of the world around him, has to look at himself in order to figure out what he's feeling. Mirrors, scattered through this novel's American and European settings, give Tom a tool by which to make sense of his own emotional state: he often catches a glimpse of his own grimace, realizes that he is on the verge of tears, and acts accordingly by changing his expression or confronting the source of his negative feelings. This motif allows Highsmith to describe her main character's appearance through a somewhat objective lens, all the while remaining deeply rooted in Tom's perspective.
Water (Motif)
One of Tom Ripley's most debilitating fears is of water, thanks to the fact that both his parents drowned when he was a young child. Over the course of the novel's action, he overcomes this particular fear in a narrative arc that is very nearly touching, except for the fact that it is rooted in violence and death. Tom kills Dickie on a boat, nearly drowning in the process and overcoming his fear out of a greater desire for revenge, money, and a new identity. After this, his fear seems almost to disappear, though he rarely chooses to be in the water: he rides gondolas in Venice and cheerfully, triumphantly sails across the sea to Greece. Tom's evolving relationship to water shows how much confidence and competence he gains from his crime spree—essentially, he trades fearfulness for bloodlust.
Art (Motif)
Most characters in this book seek some kind of artistic and aesthetic fulfillment, with varying degrees of skill. Dickie knows that he is a mediocre painter but finds joy in his work anyway, Marge disappears for days at a time to write, and even the traveling socialites Tom parties with in Venice collect art and decorate their homes obsessively. Tom pursues this artistic fulfillment more intensely than anyone. He constantly seeks beauty, and, in fact, loves well-made objects so much that he is willing to kill and steal in order to acquire them. He also loves to imaginatively disappear into a role, practicing with the same devotion Dickie and Marge display—and, again, he is willing to kill Dickie in order to do so. Everyone, Highsmith suggests, needs art and beauty in their life in order to be happy. At the same time, the pursuit of art and beauty isn't always a good in itself here, with Tom's own actions serving as a sobering reminder.