A model holds a 12.03-carat blue diamond during a press preview by auction house Sotheby’s in Geneva on Nov. 4, 2015. Hong Kong tycoon Joseph Lau was the top bidder for the 1“Blue Moon” diamond that sold Wednesday night for a record-setting $48.5 million.

A Hong Kong billionaire tycoon who has been convicted of corruption paid a total of $77 million at auctions in Geneva for two large and rare colored diamonds for his daughter, his office said Thursday.

Joseph Lau was the top bidder for the 12.03-carat “Blue Moon” diamond that sold Wednesday night for a record-setting 48.6 million Swiss francs ($48.5 million), said a spokeswoman for Lau, who declined to give her name. Sotheby’s said the buyer promptly renamed the pricier gem “The Blue Moon of Josephine.”

Lau was also the buyer of a 16.08-carat vivid pink diamond that sold for 28.7 million Swiss francs ($28.5 million) auctioned by Christie’s the night before, she said.

The buyer renamed that diamond “Sweet Josephine,” Christie’s said.

“Yes, the two diamonds are bought by Joseph Lau,” said the spokeswoman, who added that they were named after Lau’s 7-year-old daughter.

The blue diamond, set in a ring, was said to be among the largest known fancy vivid blue diamonds and was the showpiece gem at the Sotheby’s jewelry auction.

The Blue Moon — named in reference to its rarity, playing off the expression “once in a blue moon” — topped the previous record of $46.2 million set five years ago by the Graff Pink, Sotheby’s said. The diamond also set a new record of more than $4 million per carat, capping the daylong high-end jewelry sale that reaped roughly $140 million.

Lau, a property developer with a fortune estimated by Forbes at $9.9 billion, has a habit of snapping up expensive gems for his children.

At a Sotheby’s Geneva auction in 2009, he bought another blue diamond, paying a then-record $9.5 million for the 7.03-carat “Star of Josephine.”

Last November, he also bought two gems for another daughter, 13-year-old Zoe, his spokeswoman said. One was a 9.75-carat blue diamond that he named “Zoe Diamond” after buying it for about $33 million at a Sotheby’s auction in New York.

He also spent 65 million Hong Kong dollars ($8.4 million) for a 10.1-carat ruby and diamond brooch at a Christie’s Hong Kong auction.

He named that one “Zoe Red.”

Lau was convicted last year by a Macau court of bribery and money laundering and sentenced to more than five years in prison. But Lau, who didn’t attend the trial, has remained free by avoiding travel to the former Portuguese colony, which doesn’t have an extradition treaty with nearby Hong Kong. Both cities are specially administered Chinese regions.

“Tonight we set a new world record, a new auction record for any diamond, any jewel, any gemstone, with the sale of the Blue Moon diamond,” said auctioneer David Bennett in Geneva. He specified the price as $48,468,158. “I have never seen a more beautiful stone. The shape, the color, the purity — it’s a magical stone.”

The polished blue gem was cut from a 29.6-carat diamond discovered last year in South Africa’s Cullinan mine, which also yielded the 530-carat Star of Africa blue diamond that is part of the British crown jewels, and the Smithsonian Institution’s “Blue Heart” discovered in 1908.

Sotheby’s says experts took five months for an “intense study” of the original Blue Moon diamond, and a master cutter took another three months to craft, cut and polish the stone. The auction house said in a video that the Cullinan mine was the “only reliable source in the world for blue diamonds,” and only a tiny percentage of those found in it contain even a trace of blue.

Blue diamonds are formed when boron is mixed with carbon when the gem is created.

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