The Hope Diamond was allegedly cursed, with each successive owner supposedly meeting an untimely death or beset by other personal tragedy. This curse was attributed to its rumored origin: having originally been stolen by a French merchant, Jean-Baptiste Tavernier, in the mid-1600s from a Hindu temple in India. The gem was allegedly inset as one of two eyes in an idol of the goddess Sita. Angered by the theft, Hindu priests cursed the diamond, or so the story went. Because of its distinct blue-ish hue, this diamond came to be called the "Tavernier Blue" and later the "French Blue."
Part 1 of this episode of "In Search Of..." (embedded below) repeats this legend and adds menacingly that Tavernier was later killed when he was torn apart by wolves, supposedly a consequence of the curse. In reality, he lived to the age of 64. And this whole story was a fiction, having first been relayed in sensational newspaper articles in 1908 and 1910, and them embellished by owner Pierre Cartier when he sold it to American socialite Evalyn Walsh McLean in 1911. It was all legend, based in part on an 1868 novel The Moonstone, as well as on the legends surrounding other famous diamonds of the time, most notably the Koh-i-Nor diamond. In reality, the Tavernier Blue diamond is now widely believed to have been mined from the Kollur mine in what is today the Andhra Pradesh state in India. Tavernier simply bought it during one of his five voyages to India between 1640 and 1667.
In 1669, Tavernier sold it to French King Louis XIV. It resided with the French court until the French Revolution, when it was stolen in 1792 while King Louis XVI was imprisoned. The French Blue was never recovered, and simply disappeared from history. But 20 years later, in 1812, precisely as the statute of limitations expired on that theft, a slightly smaller blue diamond reappeared, now owned by a London jeweler. By 1839, it passed into the possession of the wealthy Hope family, and thus acquired its current name: the Hope Diamond. From there it passed through several hands until being sold by Cartier to Evalyn Walsh McLean in 1911, in part by emphasizing its supposedly "cursed" background. (By now, the link back to the missing French Blue was assumed for the purposes of this mythic curse, without any scientific or documentary proof.) McLean at first dismissed this curse flippantly. But she later came to believe in it just as fervently, after a child of hers died very young in an accident, and then her husband's successful business fell into ruin in the Teapot Dome scandal. (He subsequently committed suicide.) In 1949, the Hope Diamond was purchased by New York jeweler Harry Winston. And it was he who donated it to the Smithsonian Institution a decade later in 1958, famously sending it there via regular mail.
I remember seeing The Hope Diamond displayed at the Smithsonian myself as a child in the late 1970s, probably right around the time that this episode first aired in February 1979. In that display, the curse was dismissed. (But it was mentioned, and that caught my childhood imagination a little.) But consistent with the legend of the curse, the Hope Diamond was widely assumed, without proof, to simply have been cut from the French Blue diamond that was stolen in the French Revolution. And this was mentioned, too, in this Smithsonian display. Reflecting this belief, the then-Curator of Gems at the Smithsonian Institution says in part 1 of this episode that, "There's no question in my mind that the Hope Diamond as we know it now is what's left of the French Blue. Now I can't say that with any kind of proof or certainty because there's no proof in existence that we're aware of."
As it turns out, he was entirely right. On February 9, 2005, the Smithsonian Institution published the findings of its year-long computer-aided geometry research on the gem and officially acknowledged the Hope Diamond is part of the stolen French Blue. And then in November 2008, the French Museum of Natural History revealed that they had discovered in their collection a lead cast of the French Blue which they had been given in 1850.Compared to the previously available drawings, the model showed numerous unsuspected facets and corrected the actual thickness of the stone, leading to CAD analysis and the creation of the first numeric reconstruction of the French Blue. This work further supported the Smithsonian's 2005 conclusions.