The Hope Spinel, a 50.13 ct. octagonal-cut stone set in a 19th-century silver and gold brooch, will be auctioned at the Bonhams London Fine Jewellery Sale on Sept. 24.
The stone was last sold in 1917. Bonhams estimates it will go for between $227,000 and $304,000.
As its name suggests, the stone was part of the collection of Henry Philip Hope, the banker and gem collector who died in 1839. Hope was the owner of the famed Hope Diamond.
Upon his death, Hope’s gem collection, which numbered 700 pieces, became the subject of an inheritance feud among his nephews, as Hope never had children of his own. Ultimately, one nephew received the bulk of the collection, and another received eight of the most valuable stones, including the Hope Diamond and the Hope Spinel.
Some stones were sold to private dealers, and the remaining pieces were sold by Christie’s in 1917. The Hope Spinel was purchased by a dealer and ended up with Lady Mount Stephen, a friend of Queen Mary. Its current owner is a direct descendent of Lady Mount Stephen.
“It not only [has] amazing provenance, but it’s also an exceptional gemstone in its own right,” said Emily Barber, U.K. jewelry department director at Bonhams. “It’s 50 carats, and the actual stone is about two and half centimeters in diameter.”
The stone is thought to be from the ancient Kuh-i-Lal mines in Tajikistan.
“We’ve had this spinel assessed by SSEF, a premiere gemological laboratory in Switzerland, which has confirmed it is from these ancient mines,” Barber said. “Due to its exceptional transparency, flawless cut, beautiful color, and large size, it’s classed as an exceptional treasure of nature.”
Another testament to its importance: Hope’s own organization of his collection.
“The treasures of the collection were kept in the sixteenth drawer [of Hope’s bespoke mahogany cabinet],” she said. “These included the Hope Diamond, the Hope Pearl (then the largest baroque natural pearl known), an emerald from the turban of Tipu Sultan, and this spinel. That the spinel and the Hope Diamond were kept together is testament to how important it is and how much Hope valued it.”