The lucrative lure of celebrity memorabilia

Joan Didion at home in her New York apartment in 2006. Picture by Marc McAndrews/Getty Amid the frenzy around the recent auction of American writer Joan Didion's effects, it was a handful of seashells and stones - collected from beaches over the years and left to gather dust in a drawer - that seemed most surprising. The estimate was a modest $100, the eventual price $7,000. For seashells. Why? Because they were gathered by a writer who was as aloof and remote as she was revered - as the auction proclaimed, 'an American icon'. As such, Didion's effects - everything…