Oscar Wilde wrote that a man who knows the price of everything and the value of nothing is a cynic. In 2007, Wilde would call that person an art collector.

The billion-dollar market for art and antiques is in a period of distinct uncertainty right now—described by New York appraiser Victor Wiener as “shifting sands”—following a long series of record-setting auctions. Sales at Sotheby’s and Christie’s International for the year’s auction season, which traditionally ends in July, totaled $6.2 billion, up from $4.3 billion the previous year. Collecting art has recently achieved a breadth of social cachet and popular interest not seen in the past half-century. The rising tide has lifted most boats, and while Picassos have gone for astonishing prices, there have also been recent record bids for Andrew Wyeth paintings ($10.3 million), French Art Deco ($5.3 million for a pair of elaborate gilt-bronze jardinieres by Armand-Albert Rateau), and even vintage clothing ($22,800 for a Bob Mackie gown). The frothiness has been most evident in fine art, where unlikely price gulfs have opened between the work of new and established artists, and even within a body of work by the same artist.

That’s a marked change from prior art booms, during which the traditional fundamentals of supply and demand, rarity, and historical significance still applied. This time, it has been chaos. “The art market is totally out of whack right now,” says collector Scott Black, whose Monets, Renoirs, and Cézannes hang on the walls of the Museum of Fine Arts in Boston. Black, president of Boston investment advisers Delphi Management, says the new money that has fueled the steep price climb in the art market has no point of reference, and there’s no sense of what a particular work should really cost. In 1992, Black bought a Paul Signac painting for nearly $660,000; it’s now on view at the M.F.A. Last summer, a later, lesser work by the artist sold for nearly $8 million. “That’s an out-of-your-ever-loving-mind price,” Black says.

But with large fall auctions in New York approaching, the confusion has been compounded by the recent turmoil in the financial world. Is the $73 million Mark Rothko that sold in May a lasting reevaluation of the market for that artist, or a giddy fluke? To appraisers who value works for estate, tax, and insurance purposes, the answers are elusive. There’s a palpable feeling that prices at the fall auctions will inevitably reflect the current nervousness on Wall Street. But since little art has sold since the big spring events, which preceded Wall Street’s summer swoon, there’s no hard evidence that this is happening. The result? Art is generally being estimated and appraised as though the market is still strong, albeit with the understanding that the October sales in London and November sales in New York could be the beginning of a correction.