The second evening session of the now historic auction of the Collection Yves Saint Laurent et Pierre Bergé, elaborately staged at the Grand Palais by Christie’s in association with Pierre Bergé & Associes, took over five hours, and yielded results even the most experienced dealers couldn't comprehend.

The session of 20th Century Decorative Arts was filled to the hilt with rare Art Deco objets, and all but seven of the 150 lots on offer sold, for a total of €59,155,050 ($76,540,719), trouncing the pre-sale estimate of €19–28.3 million. The tally smashed the previous record for any Art Deco sale, easily eclipsing the €50,736,020 single-owner sale of Claude and Simone Dray at Christie's Paris in June 2006.

Ten lots sold for over €1 million, and the buy-in rate was just 5 percent by lot and 2 percent by value. Ten artist records were set.

The continuing hot pace of huge prices for works judged to be of outstanding quality drove the sale, just as they did for Monday evening’s record-shattering €206,154,600 sale of Impressionist and Modern art.

The undisputed star of tonight’s session was Eileen Gray, whose unique and extraordinarily lavish The Dragons armchair from circa 1917–19 fetched a jaw-dropping €21,905,000 (est. €2–3 million).

The chair, boasting a Symbolist-inspired sculpted wood frame depicting the intertwined bodies of two dragons, went to storied Paris furniture dealers Cheska and Robert Vallois, who are now two-time owners of the piece. According to the auction catalogue, the couple sold it in 1971 to a private collector; they had acquired it from Parisian tastemaker Susanne Talbot, who had it directly from Gray.

To put this extraordinary price in perspective, the former high for any 20th-century piece of furniture was set at Christie’s New York in June 2005, when a unique oak-and-glass table by Carlo Mollino sold for $3.8 million, and the only piece of furniture from any period that has ever sold for more at auction than tonight’s Gray chair was the 18th-century Badminton Cabinet that sold at Christie's London in July 1990 for £19,045,250 (€27,463,250).

Even the auctioneer, Frederic Chambre, vice-president of Pierre Bergé & Associes, who deftly navigated the bidding on the chair, expressed astonishment at the price. "I expected between €5 and 7 million, not €19.5 million," he said, referring to the hammer price before the buyer's premium was added.

But Simon Andrews, director of 20th-century decorative art and design at Christie's London, defended the bidding fever, which turned into a one-on-one duel after the €3 million mark. He described the Gray record as the result of "two people with the passion and the means, not madness."

Either way, it’s a brave new world for Gray: Tonight’s sale obliterated the designer’s previous record of €380,000, set at Beaussant Lefèvre in Paris in December 2003 by a lacquer-on-panel screen. In fact, all four Gray objects on offer tonight crushed that result: An outstanding and rare enfilade with six pairs of square sectioned legs from circa 1915–17 made €3,985,00 (est. €3–5 million); a console from before 1920 made €2,305,000 (est. €1–1.5 million); and the quirky Suspension satellite chandelier in cream paint and aluminum from circa 1925 sold for €2,977,000 (est. €600–800,000).

Another Art Deco standout lot was Jean Dunands Deux Vases Monumentaux from 1925 (est. €1–1.5 million), two vessels with geometric decorations in red lacquer, gold, and silver on a black lacquer ground and gently domed black marble lids. The pair soared to €3,089,000.

It seems that Christie’s investment of close to €2 million — for staging the pre-sale exhibition and auction at the Grand Palais and publishing the lavish set of catalogues for the six sessions — paid off handsomely, since the low estimate for the entire marathon was exceeded in the first evening session, and the low estimate for tonight's session was met by the Dragon chair alone.

“We know now it created the audience for the sale,” said Christie’s president Marc Porter shortly after Portrait d’Alfred et Elisabeth Dedreux, a strange 19th-century painting by Théodore Géricault that looked more like the work of Balthus, sold in the afternoon Old Masters session to dealer Alain Tarica for €9,025,000 (est. €4–6 million), “and it gave tremendous confidence in the Yves Saint Laurent taste to those who were buying. The glamour of it and scale of it reminded everyone of his eye.”

In tonight's session, it wasn’t just Art Deco that went over the moon, as evidenced by François-Xavier Lalannes offbeat conversation piece, The YSL Bar from 1965, complete with horn-shaped cocktail shaker, which made €2,753,000 (est. €200–300,000).

“I thought it would make a million,” said London dealer Ben Brown, who represents Lalanne and his wife, Claude, in the U.K., right after the bar sold to a telephone bidder, "but not two and a half million.” François-Xavier Lalanne died in December.

The result smashed his former mark, set at Christie’s Paris in December 2005, when Collection Troupeau De Moutons (in nine parts) from 1968 sold for €280,000.

Claude Lalanne did pretty well herself this afternoon, when her grandly scaled set of 15 mirrors with branches cast in gilt bronze and galvanized copper hit €1,857,000 (est. €700,000–1 million).

In a night of mostly remarkable results, works that had come to Saint Laurent and Bergé by way of the storied collection of modernist tastemaker Jacques Doucet fetched less impressive prices than some expected.

A specially commissioned pair of leopard-skin cushioned banquettes in palm wood frames from circa 1928–29 by Gustave Miklos, for example, reached €1,745,000, missing the pre-sale estimate of €2–3 million. Still, the pair eclipsed Miklos’s previous mark, set at Camard & Associes in June 2005, when Jeune Fille (1927) made €1,400,000.

A Pierre Legrain lot with Doucet provenance, meanwhile — a curule stool of African inspiration in stained beech wood with curved seat from circa 1920–25 — achieved its goal, selling for €457,000 (est. €400-600,000), but failed to top Legrain’s previous record, set at Camard & Associes in November 2006 when Seige Curule from 1921 made €549,115.

For all the marathon sale’s drama, however, some people were shaken and confounded by the results.

Early in the extraordinary evening session, shortly after the first of the Eileen Gray pieces sold, New York collector and dealer Jose Mugrabi left his seat to observe, “I think this sale is close to vulgar. You couldn't sell these pieces in any other place for even the commissions they're bringing. People are hypnotized. They don't know what they’re buying.”

That sense of disbelief that prices could go so high for 20th-century decorative art, and, in the case of the Gray’s Dragon Chair, even higher than for Piet Mondrians record-breaking Composition avec bleu, rouge, jaune et noir (1922), which made €21,569,000 last night, will take some time absorb. It’s unclear whether tonight’s result will represent a kind of one-off, mad-hatter price or become the harbinger for a new price structure in the field.

Judd Tully is Editor at Large of Art+Auction.