The Mellon Blue: A 9.51-Carat Masterpiece in Fancy Vivid Blue

A Christie's employee displays the Mellon Blue diamond ring (The Independent, 2025)

A Jewel of Exceptional Purity and Prestige

Few diamonds can claim the pedigree, rarity, and impeccable beauty of the Mellon Blue—a 9.51-carat Fancy Vivid Blue diamond that recently captured the attention of global collectors after selling for $26.6 million at Christie's Geneva.

Named after its former owner, Rachel "Bunny" Mellon, a celebrated American arts patron and philanthropist, the diamond spent decades as part of a private collection, originally set in a pendant. Its transformation into a ring has only elevated its elegance and collectibility.

Gemological Excellence

Certified by the Gemological Institute of America (GIA) as Fancy Vivid Blue—the highest colour grading for blue diamonds—and Internally Flawless, the Mellon Blue belongs to an elite class of natural coloured diamonds.

Key Attributes:

• Weight: 9.51 carats

• Colour: Fancy Vivid Blue

• Clarity: Internally Flawless

• Cut: Modified brilliant-cut

• Origin: Natural, untreated

  
  

According to Max Fawcett, Christie’s global head of jewellery, the Mellon Blue is remarkable for its unmodified form. Unlike most modern diamonds that are recut to intensify colour, this gem maintains its original proportions and natural vibrancy, making it both scientifically and historically unique.

“When you have great shape and great colour, you’re looking at the gem of gems,” Fawcett noted.

A Blue Diamond Worthy of Investment

Blue diamonds remain one of the rarest and most sought-after assets in the world of gemstone investment. Their supply is severely limited, with only a small number of vivid blues discovered each year—many under one carat.

The Mellon Blue stands apart not only due to its size and flawless clarity, but also for its provenance. Its connection to Bunny Mellon adds a layer of cultural and historical value, enhancing its allure among high-end collectors.

Legacy and Timeless Elegance

While the final price of $26.6 million is significant, it reflects a broader trend: ultra-rare colored diamonds are retaining and increasing value over time. Originally sold in 2014 for $32.6 million as a pendant, the Mellon Blue’s reemergence in ring form confirms that fine colored diamonds are not just adornments—they are appreciating assets.

The Gem of Gems

The Mellon Blue is more than a ring—it's a symbol of elegance, rarity and enduring value. As blue diamonds become even harder to source, pieces like this offer both emotional and financial return for those with an eye for timeless beauty.

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