A private collector from Japan acquired a rare 88.22-carat flawless diamond, which he named “Manami Star” after his eldest daughter, for HK$108 million (US$13.8 million) at a Sotheby’s auction in Hong Kong.

Described as “perfect according to every critical criterion such as colour, clarity, cut and carat,” the stone is one of only three oval diamonds of over 50 carats to appear at auction “in living memory,” according to Sotheby’s.

The 88.22-carat, D-colour, Type IIA oval brilliant diamond is also the largest to be auctioned in over five years.

The diamond beat pre-sale estimates of HK$88 million to HK$100 million (about US$11.2 million to US$12.7 million) and established a price per carat of HK$1,224,133 (US$156,150).

Patti Wong, Sotheby’s Chairman in Asia, commented, “We were thrilled to handle a diamond of such rarity, which now takes its place in the roster of top white diamonds to have come to the market here at Sotheby’s Asia.”

As with the Koh-i-noor diamond and the Cullinan I, which are part of the British Crown Jewels, the stone belongs to the rare subgroup comprising less than 2 percent of all gem diamonds, known as Type IIA. Diamonds in this group are the most chemically pure type of diamond and often have exceptional optical transparency.

The 242-carat rough stone that yielded the diamond was discovered in Botswana in the Jwaneng mine, which is owned in partnership by De Beers and the government of Botswana, and known for producing roughs of the highest quality. Following its discovery, the rough was cut and polished over a period of months to produce a symmetrical and striking oval brilliant diamond, revealed Sotheby's.