I think of this song every time I see someone wearing Louboutins with their shiny red soles. The meaning of the song is fairly obvious from its opening line, of course- “she’s a rich girl, she don’t try to hide it/diamonds on the soles of her shoes”. While the larger theme of the song is about love across class boundaries, I think the line says a lot about conspicuous wealth and the lengths the middle and upper class go to disavow their privilege: wearing their wealth against the dirty ground. Perhaps the rich girl in the song is deliberately doing this to show her poor boyfriend how little she cares about the social divide between them.
As a poor girl, I can never really relate to the rich girl/poor boy trope! However, I can appreciate great songwriting and a clever turn of phrase which is exactly what Paul Simon has done here.