A spectacular 9.51-carat fancy vivid blue diamond once owned by American art collector Rachel Lambert “Bunny” Mellon has just sold for $25.5 million USD at Christie’s Magnificent Jewels auction in Geneva. Known as the Mellon Blue Diamond, this internally flawless, pear-shaped gem remains one of the rarest blue diamonds ever discovered.

Despite its extraordinary beauty and provenance, the Mellon Blue fetched 22% less than it did 11 years ago when it last appeared at auction — and almost 60% less in real terms when adjusted for inflation. This highlights a fascinating shift in the global diamond market, where even ultra-rare coloured diamonds are not immune to changing investment sentiment and evolving buyer preferences.

Back in 2014, the same diamond sold for $32.6 million USD at Sotheby’s, setting a world record at the time for a blue diamond. That amount would equal roughly $44.7 million USD in today’s value, meaning that although the latest sale remains impressive, the market has clearly adjusted.

Christie’s had estimated the gem between $20 million and $30 million, underscoring the ongoing allure of storied jewels despite softer luxury demand worldwide.

Rahul Kadakia, Christie’s Chairman of Global Luxury and President of Asia Pacific, commented after the sale:

“It was a true honour to offer for sale the exquisite Mellon Blue Diamond here at Christie’s Geneva. It was another notable moment for Christie’s Luxury, evidencing the elite appetite amongst collectors for extraordinary and storied gems.”

The winning bidder was reported to be a collector from Hong Kong, continuing the long-standing global fascination with high-value blue diamonds.

The record for the world’s most expensive blue diamond, however, still belongs to two legendary stones:

• The 14.62-carat Oppenheimer Blue, sold by Christie’s in 2016 for $57.5 million USD
• The 15.10-carat De Beers Cullinan Blue, sold by Sotheby’s in 2022, also for $57.5 million USD

These sales reflect the incredible scarcity of such gems — blue diamonds make up less than 0.1% of all diamonds, and only 1% of those are graded as fancy vivid.

Bunny Mellon’s Legacy
Bunny Mellon, who passed away in 2014 at the age of 103, was known for her timeless elegance and sophisticated taste. As heir to the Listerine fortune and wife of financier Paul Mellon, she was one of America’s most prominent art collectors. She also designed the White House Rose Garden and curated an exceptional art collection, including two Rothko paintings that sold for $76 million USD at Sotheby’s.

When Christie’s announced the re-sale earlier this year, Kadakia described Mellon’s legacy as one that continues to enhance the diamond’s appeal, tying it to “a sophisticated aesthetic and cultural prominence.”

The auction room in Geneva was reportedly filled with excitement — and heat — as bidding intensified, prompting the auctioneer to open a window mid-sale to cool the room.

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What This Means for Today’s Diamond and Gold Sellers

While the Mellon Blue represents the highest echelon of the jewellery world, its sale reflects a broader trend: luxury asset prices fluctuate, and timing can make all the difference when selling.

For everyday investors and jewellery owners, it’s a reminder that expert valuation is key before selling diamonds or gold. Knowing the true market value of your jewellery can help you secure the highest price possible.

At The GoldCompany, our specialists offer free evaluations and instant cash payments for gold, silver, and diamond jewellery. Whether it’s an heirloom piece, broken jewellery, or an item you simply no longer wear, our team ensures you receive Sydney’s best prices, backed by trust and transparency.

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Visit The GoldCompany today — Australia’s most trusted name for selling gold, silver, and diamond jewellery.
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