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 sold the raw stone to Louis XIV for the equivalent of 147 kilograms of pure gold
• The five-day Revolution heist of 1792 and how thieves butchered the French Blue down by 23 carats to hide its identity
• The smoking-gun timing: the recut diamond resurfaced in London exactly two days after the 20-year statute of limitations expired, confirmed by a 2005 CAD analysis of a leaden model
• How Pierre Cartier weaponized a made-up curse to sell the gem to Evelyn Walsh McLean, who strapped it to her Great Dane, and how Harry Winston later mailed it to the Smithsonian for $145.29