One of the main themes in “The Gift of the Magi” is that love is more valuable than material wealth.
In the story, a young couple does not have much money so they each sell something that matters to them in order to buy the other a better gift. The moral of the story is: talk to each other! Of course, the real moral is that not all wealth is in material possessions, and love is a much more valuable wealth.
The young couple has not much money, but they do have things they value.
Now, there were two possessions of the James Dillingham Youngs in which they both took a mighty pride. One was Jim's gold watch that had been his father's and his grandfather's. The other was Della's hair. (p. 3)
Della is aware that her hair is beautiful. She is very proud of it. Her hair is a symbol of her youth, and a symbol of vanity. She sells her hair to buy her husband a watch chain.
The watch is another symbol. It symbolizes time, of course. Time gets away from us, and we make decisions that we cannot get back. However, the watch also symbolizes material possessions or wealth. James sells the watch to buy Della s set of combs for her hair.
“Don't make any mistake, Dell,” he said, “about me. I don't think there's anything in the way of a haircut or a shave or a shampoo that could make me like my girl any less. (p. 5)
The irony, of course, is that each sells his or her best possession to get something nice for the other, when they value each other more than any possession.