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Rockefeller Emerald could become most expensive ever sold at auction

Christie's
Getty Images | Ben Hider
Christie's

An 18.04-carat emerald once owned by the Rockefeller family could become the most expensive ever auctioned when it comes up for sale Tuesday.

Christie's plans to auction "The Rockefeller Emerald" – a rare, untreated Colombian emerald – at its sale in New York City on June 20. The auction house estimates that the stone will sell for between $4 million and $6 million.

"This is supremely natural beauty," said Rahul Kadakia, Christie's International Head of Jewellery. "This truly is the finest emerald that's ever come up for sale at auction, or anywhere else in the world."

Rockefeller Emerald. Courtesy of Christie's

While most emeralds require an oil treatment to enhance their brilliance and color, the Rockefeller rock is unique because it has not received any type of enhancement.

John D. Rockefeller, Jr. originally acquired the emerald in 1930, as the centerpiece of a brooch he gave to wife, Abby Aldrich Rockefeller. After her death in 1948, the brooch was disassembled and the gems distributed among her children. The largest emerald became the property of their youngest son, David Rockefeller, who commissioned famous jewelry designer Raymond Yard to set it onto a diamond and platinum ring.

"The Rockefellers are like American royalty," said Kadakia. "The provenance will also add a lot more to the emerald than just what it's worth."

If the emerald hits its high estimate of $6 million, it will break the world auction record for emerald price per carat. If it exceeds its high estimate, it could become the most expensive emerald ever auctioned. Both records are currently held by the 23.46-carat emerald brooch once owned by Elizabeth Taylor, which was auctioned for $6.6 million by Christie's in 2011.

Christie's said The Rockefeller Emerald's price estimate is based only on the quality and rarity of the stone, and the price the emerald fetches at auction will likely be bolstered by its history.

The Rockefeller Emerald will come up for sale, fittingly, at Christie's headquarters in Rockefeller Center.

"It's very, very cool that we have this city within a city, selling the stone that belonged to the man who built it."

For more record-breaking rocks, check out CNBC's "Secret Lives of the Super Rich."

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