During this season, Sotheby's Hong Kong presented the largest Fancy Vivid Blue diamond in auction history. Weighing 15.1 carats, it was valued at HK$380 million dollars – topping all lots.

On 27 April, the international auction house sold the diamond between two main events – Modern and Contemporary Art Evening Auctions. It is called The De Beers Cullinan Blue and garnered HK$450 million (around US$57.4 million) dollars – equalling the auction record for blue diamonds.

This present diamond is the highest Fancy Vivid Blue grade – awarded to 1 per cent of blue diamonds by the Gemological Institute of America (GIA). Boasting exceptional clarity, it is the largest internally flawless step cut vivid blue diamond that the GIA ever graded.

15.1-carat Fancy Vivid Blue diamond, internally flawless
Estimated to fetch more than HK$380,000,000
Hammer Price: HK$390,000,000  
Sold: HK$450,925,000 (US$57.5 million)
Auction House: Sotheby’s Hong Kong
Sale: The De Beers Cullinan Blue Auction  
Date: 27 April 2022

The bidding started at HK$310 million dollars. After 11 bids, the hammer was dropped at HK$390 million dollars. The winning bid was by Wenhao Yu, Chairman of Jewellery and Watches Department, Asia; for his client with paddle number 101. In the end, it sold for HK$450 million (around US$57.4 million) dollars with buyer’s premium – equalling the Oppenheimer Blue Diamond as the most expensive blue diamond ever sold at auction.

Due to exchange rate, the sale prices of the two blue diamonds vary in different currencies:

1. Oppenheimer Blue, 14.6 carats｜Christie’s Geneva, 2016 | Sold: CHF 56.8 million (HK$446.8 million / US$57.5 million)
2. De Beers Cullinan Blue, 15.1 carats｜Sotheby’s Hong Kong, 2022 | Sold: HK$450 million (CHF 55.6 million / US$57.5 million)

Based on the above, we compare the sale prices in US dollars. Since both fetched US$57.5 million dollars – the most expensive blue diamond auction record is split evenly.

This diamond comes from De Beers – the world's leading diamond company in production and distribution. In 2021, the rough blue diamond was mined at the Cullinan mine – part of a few mines in the world that can extract blue diamonds.

This South African mine is one of them – responsible for most of the world's blue diamond production. Many world-renowned diamonds are also derived from this mine – such as the world's largest clear cut diamond – the Great Star of Africa, which weighs 530.2 carats.

Among the rarest of all coloured diamonds, their blue is usually caused by the presence of trace amounts of the rare element boron within the diamond crystal lattice. These elements add to their desirability.

Cut in a rectangular step-cut, it makes this diamond look more elegant. Also, given that diamonds are the hardest material on earth, great skill and precision is needed to cut them. With blue diamonds, the challenge is even greater: because of their formation, every faceting process of a blue diamond demands extreme care and precision. There is no room for miscalculation – any error would result in a loss of colour and destruction of the beauty.

Throughout the ages, blue diamonds are highly prized by collectors across the world – with spectacular auction results. Some of the most valuable diamonds were acquired by Hong Kong real estate tycoon, Joseph Lau.

In 2014, Lau spent US$32.6 million dollars on a 9.75 carat Fancy Vivid Blue diamond at Sotheby’s New York. He named it The Zoe Diamond after his daughter. A year later, in 2015, Lau acquired a 12.03 carat Fancy Vivid Blue diamond for US$48.6 million dollars at Sotheby’s Geneva. Dedicating to his daughter, he named it The Blue Moon of Josephine; and it is still the most expensive diamond per carat in auction history.