GENEVA -- Christie's auctioned off the Archduke Joseph Diamond for nearly $21.5 million Tuesday night, a world auction record price per carat for a colorless diamond.

The Archduke Joseph Diamond was the first of two out-of-this world diamonds being auctioned off this week in Geneva. Sotheby's on Wednesday will auction what it calls an exceptionally rare fancy deep blue briolette diamond of 10.48 carats expected to get up to $4.5 million.

Christie's kicked off Geneva's jewelry auctions, held in five-star hotels along the Swiss city's elegant lakefront, that seem a continent if not a world away from the grim austerity gripping much of Europe.

The Archduke Joseph Diamond went for $21,474,525 including commission at Christie's auction. That was well above the expected $15 million and more than triple the price paid for it at auction almost two decades ago. The 76.02-carat diamond, with perfect color and internally flawless clarity, came from the ancient Golconda mines in India.

The seller, Alfredo J. Molina, chairman of California-based jeweler Black, Starr & Frost, said immediately afterward that there were two main bidders and that he was delighted with the result. Molina said the winning bidder, who wished to remain anonymous, is going to donate the diamond for display at a museum.

"It's a great price for a stone of this quality," Molina told The Associated Press. "It's one of a kind, so it's like saying 'Are you pleased when you sell the Mona Lisa?' Or 'Are you pleased when you sell the Hope Diamond?' It's all what the market will bear, and the stone sold for a very serious price."

Named for Archduke Joseph August of Austria, the great-grandson of both a Holy Roman emperor and a French king, the diamond passed to his son, Archduke Joseph Francis, who put it in a bank vault, then to an anonymous buyer who kept it in a safe during World War II. From there it surfaced at a London auction in 1961, then at a Geneva auction in 1993, when Christie's sold it for $6.5 million.

It wasn't the only mega-diamond to go under the hammer at Tuesday's auction in the hotel room packed with well-heeled bidders. Beneath a row of three enormous chandeliers that cast panther-like shadows on the ceiling, the participants eagerly pounced at the jewels while competing with bidders from around the world calling in to Christie's employees seated in rows on both sides of the room.

But perhaps the buyers weren't entirely immune to the harsh financial climate in Europe - or at least some Geneva version of it. Two plus-sized diamonds did not sell Tuesday night. A yellow diamond with 70.19 carats failed to sell because the final bid was 2.8 million Swiss francs, just slightly below the reserve price. A 12.16 carat pink diamond didn't sell because the final bid was 1.8 million francs, well under the reserve price.

On Wednesday, in addition to the blue briolette diamond, Sotheby's also is putting on the block a conch pearl, enamel and diamond Cartier bracelet that formerly belonged to Queen Victoria Eugenia of Spain that's expected to sell for up to $1.4 million.

The Archduke Joseph Diamond joins a long list of other fabulous jewels, watches and other luxury goods sold in Geneva. Here's a look at the city's most eye-popping diamonds put up for auction in recent years:

Royal connections

In May 2012, Sotheby's sold the 34.98 carat Beau Sancy diamond to an anonymous bidder for $9.7 million. Marie de Medici had worn it at her coronation as Queen Consort of Henry IV in France in 1610. Then the diamond passed among the royal families in France, England, the Netherlands and Prussia. It was sold by the Royal House of Prussia.

Sotheby's also sold for $3.87 million the Murat Tiara, a pearl-and-diamond tiara created for the marriage of a prince whose ancestors included the husband of Caroline Bonaparte, Napoleon's sister. Christie's auctioned off a 32.08-carat Burmese ruby and diamond ring that sold for $6.7 million, a world record price for a ruby sold at auction.

Pear-shaped

In November 2011, the Sun-Drop Diamond of South Africa, a giant pear-shaped yellow gem weighing 110.3 carats, sold for more than $10.9 million at auction, beating previous records for a jewel of its type. Including commission, the unidentified telephone bidder paid almost $12.4 million for the gem. Other lots at the $70 million sale included a white cushion-shaped diamond weighing 38.88 carats that sold for almost $7 million, including commission.

Heart-shaped

In May 2011, Christie's fetched $10.9 million for a 56-carat heart-shaped diamond that was internally flawless and $7.1 million for a 130-carat Burmese sapphire. Sotheby's got $12.7 million for a rare emerald-and-diamond tiara that a fabulously wealthy German prince, Guido Henckel von Donnersmarck, commissioned for his second, Russian-born wife around 1900. An intensely pink 11-carat diamond from the mines of India sold for $10.8 million.

Intensely pink

In November 2010, a rare pink diamond smashed the world record for a jewel at auction, selling for more than $46 million to well-known London jeweler Laurence Graff. Four bidders competed for the pink diamond, which was last sold 60 years earlier by New York jeweler Harry Winston. The seller chose to remain anonymous. The 24.78-carat "fancy intense pink" diamond immediately became known as "The Graff Pink."

Associated Press