"About Gatsby! No, I haven’t. I said I’d been making a small investigation of his past."
"And you found he was an Oxford man," said Jordan helpfully.
"An Oxford man!" He was incredulous. "Like hell he is! He wears a pink suit."
"Nevertheless he’s an Oxford man."
"Oxford, New Mexico," snorted Tom contemptuously, "or something like that."
"Listen, Tom. If you’re such a snob, why did you invite him to lunch?" demanded Jordan crossly.
"Daisy invited him; she knew him before we were married – God knows where!" (7.230-236)
Tom demonstrates that wealth alone cannot make somebody fit in the upper echelons of society. They must be educated as well.
Gatsby’s foot beat a short, restless tattoo and Tom eyed him suddenly.
"By the way, Mr. Gatsby, I understand you’re an Oxford man."
"Oh, yes, I understand you went to Oxford."
"Yes – I went there."
Pause. Then Tom’s voice, incredulous and insulting: "You must have gone there about the time Biloxi went to New Haven."
Another pause. A waiter knocked and came in with crushed mint and ice but, the silence was unbroken by his "thank you." and the soft closing of the door. This tremendous detail was to be cleared up at last.
"I told you I went there," said Gatsby.
"I heard you, but I’d like to know when."
"It was in nineteen-nineteen, I only stayed five months. That’s why I can’t really call myself an Oxford man."
Tom glanced around to see if we mirrored his unbelief. But we were all looking at Gatsby.
"It was an opportunity they gave to some of the officers after the Armistice," he continued. "We could go to any of the universities in England or France."
I wanted to get up and slap him on the back. I had one of those renewals of complete faith in him that I’d experienced before. (7.208-221)
Tom tries to discredit Gatsby by attacking his education.
I graduated from New Haven in 1915, just a quarter of a century after my father, and a little later I participated in that delayed Teutonic migration known as the Great War. I enjoyed the counter-raid so thoroughly that I came back restless. Instead of being the warm centre of the world, the Middle West now seemed like the ragged edge of the universe—so I decided to go East and learn the bond business. (1.6)
Although Nick isn’t upper-upper-class, he’s still near the top of the social ladder. He went to Yale and his father also attended an Ivy League school. His legacy status gives him extra clout. Nick was also in a secret society at Yale, along with Tom Buchanan. In addition to the top-tier education that Yale bestowed on Nick, the connections that he made while a student in New Haven were just as important. His connection to Tom alone gets him into situations where usually only the wealthiest folks would be welcome.