Sam Kean

The price of diamonds can vary greatly depending on size, cut, color, and other factors, including whether they have a history. But because of the rarity of blue boron diamonds, they often fetch more money than gems of similar quality.

Even fictional characters sometimes receive unwarranted medical opinions. Doctors have diagnosed Ebenezer Scrooge with OCD, Sherlock Holmes with autism, and Darth Vader with borderline personality disorder.

All my grandchildren bake. On a Saturday, Annabel's boys, Louis and Toby, always bake. Louis makes a chocolate cake, Toby makes banana or lemon drizzle. They're 12 and 10, and they can do it totally on their own. My son's twin girls, Abby and Grace, are 14; they make birthday cakes and like to do it on their own with Mum out of the way.