Some of the names in The Moonstone have allegorical weight – they tell us something about the character. Rachel Verinder, for example, is known for her honesty. Verita is Latin for "truth," so her name reflects that honesty is just a part of her character. Mr. Septimus Luker, the art dealer, moneylender, and pawn broker, is likewise described by his name. "Lucre" (pronounced the same way as "Luker") means "money" (you might know the word "lucrative," which means "profitable"). And "Septimus" is a Latin name that means "seventh," but it also sounds a lot like "septicus," which is Latin for "rotten" or "filthy" (like a septic system). So "Septimus Luker" could roughly be interpreted as "dirty money." How appropriate, given that Mr. Luker buys stolen goods.
The Moonstone is put together as a series of first-person narratives, each from the point of view of a different character. We learn a lot about the narrator based on the way they describe the other characters, events, and from the way they address the reader. For example, Gabriel Betteredge is always comparing himself to the reader and is very chatty. At the end of his narrative, he says, "I drink most respectfully (having just done dinner) to your health and prosperity, in a tankard of her ladyship's ale." He seems like the kind of guy you wouldn't mind sitting down to dinner with, and sharing that "tankard" with. He's friendly, familiar, and chatty.
Then there's Miss Clack. She doesn't chat with the reader, or offer to toast her reader in a "tankard of her ladyship's ale." Instead, she preaches: "Oh, my young friends and fellow-sinners! beware of presuming to exercise your poor carnal reason. Oh, be morally tidy. Let your faith be as your stockings, and your stockings as your faith. Both ever spotless, and both ready to put on at a moment's notice!" (18.104.22.168).
A character's profession can tell us a lot about them in The Moonstone. For instance, Mr. Bruff is a lawyer, and he is therefore very straightforward and matter-of-fact. His dialogue is easy to understand, and his language is almost legalistic. Ezra Jennings is a doctor (or a doctor's assistant), and all he ever wants to do is help people – even if the problem isn't exactly medical, like when he volunteers to help stage a reenactment of the theft of the Moonstone to help prove that Franklin is innocent.