DiamondBuzz
Christie’s to Auction ‘Mellon Blue’ Diamond for Up to $30M in Geneva
The 9.51-carat fancy vivid blue diamond, once owned by Bunny Mellon, will headline the Magnificent Jewels sale this November.
Christie’s will offer a rare and historic blue diamond in its upcoming Magnificent Jewels sale on November 11, with the exceptional stone estimated to fetch up to $30 million.
Known as the Mellon Blue, the jewel features a 9.51-carat, pear-shaped, fancy vivid blue diamond, graded internally flawless — one of the highest accolades for clarity and color in the diamond world.
The diamond was once owned by Rachel Lambert “Bunny” Mellon, the American philanthropist, art collector, and noted horticulturalist whose garden designs can be seen at both the White House and the Palace of Versailles. Mellon, heiress to the Gillette fortune, was known for her refined taste and cultural influence.
Previously set in a pendant, the diamond was sold at Sotheby’s in 2014 for $32.6 million, where it set a then-world record for a blue diamond. It has since been recut to enhance its clarity, and is now being presented in a newly designed ring setting for this sale.

“This stunning fancy vivid blue diamond, which once belonged to America’s ‘Garden Queen,’ is among the finest colored diamonds ever to come to market,” said Rahul Kadakia, International Head of Jewelry at Christie’s. “After a very strong first half for Christie’s jewelry department, we look forward to the second half of 2025 with great confidence.”
Ahead of the auction, Christie’s will preview the Mellon Blue in Saudi Arabia, Shanghai, Hong Kong, Bangkok, and New York, allowing collectors and connoisseurs around the world a rare glimpse at one of the most exquisite colored diamonds to appear at auction in recent years.
DiamondBuzz
De Beers Group Sets Out Portfolio and Organisational Actions to Support Long-Term Value Creation
Company outlines strategic cost optimisation, portfolio streamlining and operational changes to strengthen resilience while positioning for long-term growth in the natural diamond industry.
De Beers Group is advancing delivery of its business streamlining by setting out a number of planned portfolio and organisational changes to ensure an efficient cost base that strengthens resilience in the near-term while enhancing future competitiveness and retaining optionality as industry conditions improve.
Since 2024, De Beers has been streamlining its business in line with its Origins strategy to reduce costs, divest non-core assets and prioritise investment in activities that create the most value. Significant progress has been made, with more than $100 million of annual overhead costs removed from the business, the sale or closure of a number of non-core assets and significant capital and cost reconfigurations to asset expansion projects.
Simultaneously, De Beers has reinvested in natural diamond category marketing to support the industry’s efforts to grow natural diamond demand, launching new large-scale campaigns and collaborating with key stakeholders across the value chain to foster industry-wide investment. Global consumer demand for natural diamond jewellery returned to growth in 2025, while natural diamond sales increased across US independent jewellers in 2025 and into Q1 2026, led by higher value diamonds and those promoted by De Beers’ Desert Diamonds marketing campaign.
On the supply side, global rough diamond production is now decreasing, with several producers closing mines during 2026. Whilst the increasing rarity of diamonds and the emerging signs of improvement in consumer demand are likely to support longer-term value creation, rough diamond trading conditions are expected to remain challenging in the near-term due to cyclical and industry-specific factors.
Consistent with recent actions to improve business resilience, De Beers intends to pause production at the Venetia mine in South Africa for two years to reduce costs while also rephasing capital expenditure on its underground project. This will involve critical infrastructure investment to enhance the capacity and efficiency of the mine, with the intention to support future production growth as business and industry conditions improve.
De Beers is engaging with stakeholders in accordance with relevant requirements and the company’s values as it moves through this process, and will both support impacted employees and continue to invest in its community and Social and Labour Plan commitments.
This proposed action at Venetia Mine follows the decision earlier this year to pause the Tuzo Phase 3 expansion project at the Gahcho Kué Mine in Canada.
In parallel, De Beers plans to reconfigure its global operating model to refocus and prioritise resources on the core operational businesses and reduce its central corporate cost base.
Al Cook, CEO of De Beers Group, said:

“In line with our commitment to focus and streamline our business, we are making a number of changes to De Beers to ensure greater business resilience in the near-term, while supporting long-term value creation. We recognise the protracted challenging conditions as the diamond industry evolves, though we are encouraged by signs of consumer demand growth in the US and beyond, particularly in higher quality diamonds.
Global rough diamond supply is falling, bringing more support to the market. The changes we are making to our business are focused on underpinning our efficiency now and into the future, favourably positioning De Beers in its leadership role.”
De Beers Group will maintain current production levels through its other operations, and previous production guidance remains unchanged.
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