Jewels belonging to Huguette Clark, who was dubbed the "reluctant heiress" after choosing to spend her final years living in hospitals instead of her lavish homes, sold for $21 million at auction.

"The Clark Pink", which sold for a record $15 million / Photo: Christie's

A rare 9-carat pink diamond ring that fetched more than $15 million, nearly twice its high pre-sale estimate, was the top item in the sale at Christie's on Tuesday which had been expected to total about $10 million.

Known as "The Clark Pink," the ring set a new auction record for the most valuable pink diamond sold in the United States. The buyer was U.S. diamond, gem and jewelry special Brett Stettner of Stettner Investment Diamonds, according to Christie's.

"The entire collection, which has fascinated collectors and press worldwide, achieved a total of $20.8 million," said Rahul Kadakia, Christie's Americas' head of jewelry.

"This is the second most valuable private collection sold in the United States in the last decade, just behind the legendary jewels of Elizabeth Taylor."

When the sale was announced last month, Kadakia spoke about the iconic Art Deco design and exceptional craftsmanship of the jewels and said they are emblematic of the great Gilded Age in American history.

The Clark jewels were offered as part of Christie's magnificent jewels auction, which took in just over $70 million, with 95 percent of the 304 lots finding buyers.

The top 10 lots, each commanding prices over $1 million, were snapped up by Asian, Middle Eastern, European and other international dealer and clients, as well as U.S.-based bidders.

Other highlights from the Clark collection included a 20-carat D-color diamond ring which sold for $3.1 million, beating its high estimate.

Clark, who died last year at age 104, was heir to a copper, timber and railroad fortune and had no children. Married once briefly, she shunned the social limelight and trappings of wealth, preferring to focus on her doll collection, which is reportedly worth millions.

Christie's said Clark's collection was believed to have been stored in a bank vault since the 1940s. Her estate was valued at about $400 million when she died.

Her will stipulated the establishment of a foundation to promote and foster the arts, to be called the Bellosguardo Foundation after her 24-acre ocean-front home in Santa Barbara.

Clark left nothing to any members of her family, but bequeathed millions to a nurse assigned to her in 1991 who became Clark's closest companion. The will is being contested.