How we cite our quotes: Collins doesn't use traditional chapters in The Moonstone, so the citations are a little trickier than in other Victorian novels. Citations follow this format: (Period.Narrative.Chapter.Paragraph).
Quote #1
Going round to the terrace, I found three mahogany-coloured Indians, in white linen frocks and trousers looking up at the house. (1.1.3.14)
Betteredge describes the three Indian men as "mahogany-coloured." Mahogany is a dark-colored hardwood that grows in tropical areas – primarily in Central and South America, although some trees from the South Pacific are also called mahoganies. No, this isn't just a random fun fact about trees: it shows that Betteredge's description goes beyond a (racist) reference to the skin color of the three Indian men. He also objectifies them by associating them with a kind of wood that was expensive and exotic – and obtained only by trade with British colonies – during the nineteenth century. He's associating them with exotic luxury commodities.
Quote #2
Now I am not a sour old man. I am generally […] the last person in the world to distrust another person because he happens to be a few shades darker than myself. But the best of us have our weaknesses—and my weakness, when I know a family plate-basket to be out on a pantry table, is to be instantly reminded of that basket by the sight of a strolling stranger whose manners are superior to my own. (1.1.3.16)
Generally, when a person starts to say, "Now I'm not racist, BUT," the alarm bells should start going off. But Betteredge claims, at least, that he feels suspicious, not because of the skin color of the three Indians, but because a) they're "strangers," and he doesn't like things that are strange or new, and because b) their "manners are superior" to his, which suggests that they are of a higher social class than they appear to be. All in all, Betteredge doesn't know what to make of them.
Quote #3
Here was our quiet English house suddenly invaded by a devilish Indian Diamond. (1.1.5.40)
This seems like a strange statement. After all, the Moonstone is just a rock. Betteredge is personifying it when he says that it is "invad[ing]" the house. And he doesn't just refer to it as "the Moonstone"; he calls it "a devilish Indian Diamond." By emphasizing the nationality of the gem, and the nationality of the English house, Betteredge is suggesting that there's more going on here than simply the presence of a troublesome piece of jewelry in his home. The "English house" could be read as a metonymic symbol for all of England, and the "Indian Diamond" is often interpreted as a symbol for India. So for him to say that the diamond is "invad[ing]" the house could perhaps represent the anxiety of many British citizens that the people they were colonizing and oppressing in other countries might actually come back to England and invade them.