Quote 1
"First," said Mr. Jaggers, "you should have some new clothes to come in, and they should not be working clothes. Say this day week. You'll want some money. Shall I leave you twenty guineas?" (18.83)
In telling Pip to get rid of the working clothes look, Jaggers indirectly insults Joe and indicates that Pip won't be associating with the working classes anymore. Money divides people: this seems to be first time that Pip and Joe won't look like each other.
Quote 2
"Not a particle of evidence, Pip," said Mr. Jaggers, shaking his head and gathering up his skirts. "Take nothing on its looks; take everything on evidence. There's no better rule." (40.92)
Mr. Jaggers may like to know the truth—but only so he can disguise and massage it by, say, dressing it up in a frilly outfit so it looks weak and non-murderous. (Ahem, Molly.)
Quote 3
"It is considered that you must be better educated, in accordance with your altered position, and that you will be alive to the importance and necessity of at once entering on that advantage." (18.63)
Apparently, certain kinds of education (most likely involving dead languages) are more valuable than others (like how to work a forge). Interestingly, we never get to see Pip "learning" in London, though apparently, he's at it all the time.