Conversely, when a previously unknown work by a famous artist is identified and authenticated, whoever originally bought it cheaply will make out pretty well. In 2001, for example, the Duke University Museum of Art acquired a painting in France with only two marks of identification: the initials "FG" and the year "1787." Art authenticators determined that it actually was a work by Francois Gerard, and as such probably worth two to three times what the museum had paid for it. Another painting was thought to be just an anonymous copy of a famous 18th-century Diego Velazquez painting, until Walter McCrone determined that it had been painted by 19th-century French painter Edouard Manet. Not surprisingly, the newfound "lost" Manet skyrocketed in value.

McCrone’s examination of the suspected Manet painting, which he described in a 2001 article in The Sciences, showed the extent to which scientific analysis has augmented — if not quite superseded — traditional authentication methods such as documenting an artwork’s history or submitting it to visual inspection by aficionados. McCrone began by using a fine-tipped needle to remove microscopic samples of pigment from various spots on the painting. Using a microscope, McCrone then studied the size and shape of the pigment particles. McCrone discovered that although the basic pigments were common to artists of the mid-19th century, these particular samples also had idiosyncratic characteristics — the white pigment, for example, was made up of a rare form of lead carbonate, and its particles were arranged in an unusual column-like fashion. McCrone then persuaded museum curators to allow him to take microscopic pigment samples from two known Manet paintings. He subjected all the samples to electron-probe X-ray microanalysis, an even more exacting method in which a beam of focused electrons is aimed at a pigment particle to generate X-rays, which then are analyzed to measure the precise amounts of various elements present. The result? The white pigment in the suspected Manet had come from the same production lot — and possibly the same paint tube — as the two known Manets.