Celebrating the 50th anniversary of Sotheby’s in Asia, early next month Sotheby’s Hong Kong will showcase the crown jewel of its autumn auctions – The Infinite Blue, an 11.28-carat Fancy Vivid Blue Diamond ring.

The stone’s final carat weight, ending in eight, was deliberately planned. Well-regarded as an embodiment of prosperity and auspiciousness in Asia, the form of the numerical digit when rotated is reminiscent of the universal symbol for infinity, which inspired its name.

The blue diamond ring will be offered in a stand-alone auction on 5 October, with an estimate between HK$208 and 288 million (US$26.6 and 36 million).

Blue diamonds are among the rarest of all coloured diamonds. Of all natural diamonds, less than 0.02% come in blue.

While other coloured diamonds can be found in mines worldwide, the sources for blue diamonds are incredibly limited, with the majority being unearthed in the Cullinan Mine in South Africa.

But even there, such finds are extremely rare – only 0.1% of the total mining production can produce blue diamonds, irrespective of the strength of colour.

With immense rarity, blue diamonds have been highly sought-after on the market. The current auction record stands at CHF 56.8 million (US$57.5 million), set by The Oppenheimer Blue, a 14.62-carat Fancy Vivid blue, at Christie’s Geneva in 2016.

Last year, a near tie with this record was achieved when the 15.1-carat De Beers Blue went for HK$451 million (US$57.5 million) at Sotheby’s Hong Kong.

The Infinite Blue | A Fancy Vivid Blue diamond and diamond ring

Set with a radiant-cut fancy vivid blue diamond weighing 11.28 carats, embellished with brilliant-cut and trapeze-shaped diamonds and brilliant-cut diamonds of pink tint, mounted in 18 karat white and pink gold

Clarity: VS2

Estimate: HK$208,000,000 – 288,000,000 (US$26.6 – 36 million)

Auction House: Sotheby’s Hong Kong

Sale: The Infinite Blue

Date and Time: 5 October | 8:00 p.m. (Hong Kong Local Time)

Same as those two diamonds, the rough stone of The Infinite Blue was discovered at the Cullinan Mine. Apart from blue diamonds, the mine has also yielded many of the world’s most famous diamonds, including the 530-carat Great Star of Africa, the largest faceted colourless diamond in the world.

Weighing 11.28 carats, The Infinite Blue has been graded Fancy Vivid by the Gemological Institute of America (GIA) – the highest possible colour grading, awarded to no more than 1% of the blue diamonds submitted to the GIA.

In terms of clarity, it is classified as VS2, ranking sixth on the GIA scale, meaning minor inclusions are visible under 10x magnification by a skilled grader.

To enhance its appearance, the stone has been cushioned into a radiant cut, a style that combines the dazzling sparkle of a round brilliant and the aristocratic elegance of an emerald cut. With 70 facets, it creates a mesmerizing interplay of light while camouflaging minor imperfections.

Throughout the ages, blue diamonds have been highly prized by collectors and connoisseurs across the globe. Notably, Hong Kong property tycoon Joseph Lau is renowned for his generous and high-profile acquisition of blue diamonds.

In 2014, Lau spent US$32.6 million on a 9.75-carat Fancy Vivid Blue diamond at Sotheby’s New York, and named it The Zoe Diamond after his first daughter.

The following year, in 2015, he splurged US$48.6 million on a 12.03-carat Fancy Vivid Blue diamond at Sotheby’s Geneva. Dedicating to his second daughter, he named it The Blue Moon of Josephine, which remains the most expensive diamond per carat in auction history.