What are two examples of irony in The Gift of the Magi?

One example of irony in "The Gift of the Magi" is the couple sacrificing their most prized possessions to buy gifts for each other, only to realize that their gifts are now useless. Another example is that Jim's watch chain and DELLa's hair are symbols of their love and sacrifice, yet they end up selling them to buy gifts that play off these very symbols.