The T.J. Eckleburg billboard shows materialism because of the colors described, "They look out of no face, but, instead, from a pair of enormous yellow spectacles which pass over a non-existent nose," this shows his sad, blue eyes looking through materialistic lenses and that he is God watching over the people (Fitzgerald 23).
Gatsby's car shows materialism through its color as described in the passage, "I'd seen it. Everybody had seen it. It was a rich cream color, bright with nickel..." this shows that it is yellow which represents materialism and because it is such an expensive car, everyone has seen it (Fitzgerald 64).
Two girls at one of Gatsby's parties arrive in yellow dresses which represent them, "...and gave ear to two girls in twin yellow dresses," their appearance shows their desire to be rich and have a high social status (Fitzgerald 42).