The U.S. art market appears to be on the mend. The major fall art auctions may not have sold everything on offer, but collectors showed a renewed willingness to bid up top examples of artists' work. Dealers also said inflation fears and expectations of higher bonuses in the financial markets stoked strong bidding.

New York's two chief auction houses, Sotheby's and Christie's International, brought in about $596 million combined from their semi annual sales of Impressionist, modern and contemporary art in the past two weeks. The total surpassed the houses' $409 million spring sales in May, a gain that could signal a measure of returning confidence in high-end art values.

The mood among collectors grew increasingly upbeat as the two weeks of sales progressed. At Sotheby's contemporary art sale Wednesday night, a Warhol silkscreen sold for $43.7 million, more than triple its high estimate. At a lively sale of modern and Impressionist art the week before at Sotheby's, an Alberto Giacometti sculpture sold for $19.3 million, well over its $12 million high estimate.

At Christie's, the results were more modest. The house fell short of presale estimates at its Impressionist sale and modern art evening sale Nov. 3, but it performed solidly at Tuesday's post-war and contemporary auction, led by a Peter Doig painting that sold for $10.1 million.

While just a quarter the size of the record-holding pink gem and not quite flawless, the stone's "vivid pink" is considered near perfect and the auction house has touted it as one of the best colored stones to appear in recent years.

"There are pink diamonds and then there are pink diamonds," said Francois Curiel, the international head of Christie's jewelry department. "It is extremely rare for a stone of such top quality to appear on the market with top notes in color, cut, clarity and carat weight. This 5-carat vivid pink gem combines the best of all criteria," Curiel added.

Overall, in what might be another sign that the economy is continuing its slow recovery, Christie's "New York Jewels" auction sold 91 percent by lot and 86 percent by volume.

Head of jewelry Rahul Kadakia said a total of $11.3 million changed hands at Christie's on Thursday, "in a room buzzing with excitement."

"Following our sales in Hong Kong and London, the auction in New York reaffirmed the strength of the jewelry market. We are delighted to end Christie's Spring Jewelry season with dominant market share of 65 percent in New York and 60 percent worldwide," he said.

The blue-and-white dragon vase, bearing the mark of Emperor Yongzheng (reign: 1723-1735), is one of 1,600 paintings, gems and antiques that Christie's expects to sell for HK$750 million ($96 million) at its four-day auction starting on May 24. The item once belonged to Hong Kong antiques doyen Robert Chang.

The sale will test Chinese buyers' willingness to buy from Christie's after the company's Feb. 25 sale of bronzes, plundered by foreign troops in the 19th century, which sparked outrage in China. The government imposed controls on Christie's in mainland China after the Yves Saint Laurent collection's auction in Paris. Cai Mingchao, the Chinese dealer who placed the winning $40 million bid, refused to pay.

Hong Kong is Christie's third-biggest market after New York and London and its hub for the sale of Chinese antiquities, with revenue of more than HK$1 billion last year. Christie's had a record number of Chinese buyers at its New York and London auctions this month, a sign of their growing importance, Andrew Foster, Christie's Asia president, said in an e-mail.

Christie's International's six-session sale in the Art Nouveau exhibition hall of Paris's Grand Palais raised a combined 374.4 million euros with fees ($477 million), beating estimates of 200 million euros to 300 million euros. The London- based auction house said nearly 96 percent of the 689 lots sold. Estimates don't include Christie's fees.

"After this, people will believe that it's a good thing to buy art," Pierre-Yves Machault, a Paris-based dealer, said in an interview. "It will help them understand that if you buy good things, they will keep their value -- even if you’re not Saint Laurent. It makes me more optimistic."

The biggest-grossing auction of a private collection was boosted by the quality of items on offer and the number of people who shared the taste of the late fashion designer and his former partner Pierre Berge, said collectors. The proportion of lots selling at some other auctions -- and prices of works -- have dropped in the economic slump.

With confidence in the contemporary art market now decidedly low, international auction houses are using cautious language in the lead-up to next week's big London contemporary sales. The auctions all feature works by artists whose prices soared in the boom times.

"Estimates were done taking into account the new circumstances of the market," says Phillips de Pury chairman Simon de Pury. He hastens to add that this modest approach "offers collectors great opportunities" at his sales on Feb. 12 and 13.

At Christie's, international director of postwar and contemporary art Pilar Ordovis notes that the auction house's prestigious evening sale on Feb. 11 will offer "a carefully curated selection of works of the most established artists of the last 60 years."

Christie's said the ewer, which sold to an anonymous client in the saleroom, was made for the court of the Fatimid rulers of Cairo in the late 10th or early 11th century. It was embellished in enamelled gold mounts made in 1854 by a French silversmith.

By the middle of the 11th century the Fatimid state had become so impoverished that much of the contents of the Royal Treasury had to be sold, including ewers, the auctioneer added.

Of the other six surviving examples, one is in London's Victoria & Albert Museum, two are in the treasury of the Basilica of San Marco, Venice, one is in the Cathedral of Fermo, Italy, another is in the Louvre in Paris and one was stolen from the Museum of Limoges, France, in 1980.

There was one other known ewer, but it was dropped by an employee of a museum in Florence in 1998 and shattered irreparably, according to reports.