It glows blood red in the dark, supposedly caused beheadings and madness, and is worth up to $350 million. But strip away the legend and the Hope Diamond is something far stranger: a 1.1-billion-year-old anomaly wrapped in the greatest marketing con in jewelry history.

This episode traces the true journey of the world's most famous jewel, from its formation deep in Earth's mantle to its theft during the French Revolution and its quiet donation to the Smithsonian. Along the way we separate documented science from Victorian fiction and reveal how a fabricated curse turned a gemstone into a global obsession.

• Why a single boron atom per million carbon atoms gives the stone its deep blue color and a real, scientifically documented red phosphorescent glow used to fingerprint it against fakes
• How French gem merchant Tavernier so ...