The final price, which includes fees, ended up in the middle of an estimate range between HK$145 million and HK$195 million. The anonymous buyer was an “Asian private” client. Christie’s specifies when an item is bought by a wholesaler, but this transaction appeared to be a retail sale.

The Fancy Color Research Foundation analyzed the stone before the auction, as it does with most high-profile sales, and noted that the fancy vivid blue diamond had no gray undertone, but the foundation gave it a below-average “inner-grade” of 2 on a scale of 1-4.

“Tilting the stone gently reveals interchanging “see-through”  areas on the rounded side,” the foundation wrote in a pre-auction analysis.

Despite the solid price for the Moussaieff pendant necklace, the overall Hong Kong sale fell shy of expectations, with only 186 of 291 lots sold, an extremely low rate of 64%. The lackluster result may not bode well for Christie’s upcoming sale of “magnificent jewels” on June 12, including pieces from the Peggy and David Rockefeller Collection.

The Hong Kong jewelry sale was on the last day of a series of auctions for watches, wine, and fine art that took place in the city. The sales generated mixed results, with only 68% of lots sold for a Monday auction of Fine Chinese Classical Paintings and Calligraphy that realized HK$70 million (US$9 million). The same day a sale of Chinese Contemporary Ink was 82% sold, however, realizing HK$25.5 million (US$3.3 million).

On Tuesday, the sale of Fine Chinese Modern Paintings realized HK$423.4 million (US$54.2 million) and was 74% sold, Christie’s said.

Fancy colored diamonds, especially blue, have been in high demand for some time, with steadily rising prices to match. Consider another Moussaieff piece, a 4.29-carat marquise-cut, internally flawless, fancy vivid blue diamond ring that sold for about US$11.6 million at Christie’s in November 2016 in Hong Kong. As the Diamond and Investment Intelligence Center has written, blue is “the color known to make the most commotion at jewelry auctions.”

Fancy vivid blue buyers are attracted, of course, to their brilliant natural color, but the rising prices reflect their scarcity. According to the FCRF, fancy blue diamonds rose 5% in value in the first quarter from the same period a year earlier. As a whole, the Fancy Color Research index was up 0.1% for the year, dragged down by prices for yellow and pink diamonds, which fell 1.7% and 0.6%, respectively.

Other notable Hong Kong sales included a Rockefeller pearl necklace for US$2 million and a  multi-colored diamond and seed pearl bracelet made by Edmond Chin for the House of Boghossian that sold at US$4.5 million, above its US$3.2 million high estimate. The bracelet band features flowerheads and buds amid circular-cut diamond leaves.