Christie's is set to present the 'Mellon Blue' diamond, a remarkable 9.51-carat Fancy Vivid Blue diamond, at its Magnificent Jewels auction in Geneva on November 11, 2025. This exceptional gem, graded Internally Flawless and presented as a ring, is expected to achieve a price between $20 million and $30 million.
The 'Mellon Blue' diamond boasts a distinguished history, having previously belonged to Rachel Lambert Mellon, an American horticulturist, philanthropist, and art collector widely known as Bunny Mellon. Mellon's influence extended to significant landscape design, including her work on the White House Rose Garden. Her philanthropic legacy includes the establishment of an educational institution dedicated to botany and horticulture.
Blue diamonds are exceedingly rare, deriving their color from trace amounts of boron. Scientific research suggests these diamonds form at extreme depths within the Earth's mantle, potentially over 410 miles deep. The color is believed to originate from boron carried deep into the Earth by tectonic plate movement from ancient ocean floors.
Historically, blue diamonds have consistently fetched record-breaking prices at auction, highlighting their immense desirability among collectors. A previous blue diamond from the Mellon estate sold for $32.6 million in 2014, setting a world record at the time. The upcoming auction will also feature other notable jewels, including a 6.24-carat Fancy Deep Blue diamond ring that previously held a per-carat record.
Christie's has a strong track record with high-profile diamond sales, including the Oppenheimer Blue. The 'Mellon Blue' is anticipated to join this esteemed lineage, attracting global market attention due to its extraordinary beauty and historical significance.