Gold has dropped some 13 percent in two days, the worst two-day drop since 1980, and while some traders say that it's becoming oversold, other say it's just impossible to know. That's because, according to one increasingly insistent group of market thinkers, we simply have no idea what gold is worth.
Doug Kass of Seabreeze Partners Group is among them. "The price of gold is sentiment-driven," Kass wrote to CNBC.com. "When the sentiment turns down, as it has most recently, Katie bar the doors—as there is no intrinsic value support. There is just what people are willing to pay in an auction market."
(Read More: Gold Hit by Panic Selling, Margin Calls Driving Downdraft in Other Metals, Oil)
Of course, this wasn't always so. Before 1971, the U.S. was on the gold standard. That meant that one could sell an ounce of gold to the Treasury for $35—or walk in with $35 and walk out with an ounce of gold. And some want to go back to this system, as Paul Krugman discussed in his recent New York Times column, "Lust for Gold."