The Mellon Blue. Fancy Vivid Blue Internally Flawless diamond of 9.51 carats. Estimate: US$20,000,000-30,000,000 © Christie's Images Ltd 2025 

The diamond once belonged to Rachel Lambert Mellon, known as Bunny Mellon, a symbol of American elegance and sophistication. Her refined taste extended to her jewellery, which she selected with the same care and sensitivity she brought to her interiors and gardens. 

A rare expression of nature’s brilliance and remarkable for both its intense colour and its extraordinary purity. Christie’s Geneva is proud to offer one of the finest coloured diamonds to appear on the market for decades. 

Christie's. Magnificent Jewels, Geneva, 11 November 2025