Watch: $48 Million 'Blue Moon' Diamond For 7-Year-Old Daughter

A Hong Kong billionaire bought a 12.03 carat diamond, nicknamed "Blue Moon," at auction on Wednesday evening for his 7-year-old daughter, AFP reports.

Joseph Lau, whose fortune is estimated by Forbes as $9.9 billion, bought the diamond at Sotheby's auction house in New York, only to rename it "Blue Moon of Josephine," after his daughter. He also bought a pink diamond—the largest of its kind to appear at auction—at auction house rival Christie's on Tuesday for $28.5 million.

The lucky 7-year-old was also given another $9.5 million blue diamond by her father— renamed as the "Star of Josephine"—in 2009. She is one of two children from Lau's relationship with his girlfriend Chan Hoi-wan. He has two more children from a previous marriage.