Passage: Ten years later, while walking along the Champs-Élysées, she suddenly sees Madame Forestier, who barely recognizes her in her somewhat shabby state. As the women are talking, Mathilde recounts the story of losing and replacing the necklace, and that it was because of Madame Forestier that she has lived so terribly the past ten years. Madame Forestier takes Mathilde's hands and explains that her original necklace was a fake or "made of paste", and was worth nothing more than 500 francs.

Question: At most, what was the worth of the fake necklace?
500 francs