Hall says it's become amazingly cheap to get artists in China or Taiwan to make copies of great art "for like $100… on real canvas, with real paint."
"They put them in pizza ovens and bake them until the paint cracks, and it looks real old," he says.
Kelly also notes that huge advances in copying "technology is making it more difficult for us to detect forged works."
"It's of such high quality… it's difficult for anyone but a real expert to tell if it is in fact a forgery," he adds.
Hall says most of these fakes are fairly easy to spot if you have the knowledge and experience. "A painting 150 years old is real hard to copy… It's almost impossible to fake if you know what to look for," he says.
One of the best copies Hall ever personally encountered was a work allegedly by Peter Paul Rubens. "It was done in Armenia, then smuggled into the U.S., then made to look old," he says. "It was very well done."
Potentially, a high-quality Rubens fake could be worth a fortune. (In 2002, one newly discovered work by the artist sold for $76.2 million.) Hall says the owner of that expert Rubens copy he saw never did sell the forgery.
Really high-class art forgers, of course, have been able to fool the experts. Confessed fakers like Ken Perenyi (author of the recent book Caveat Emptor: The Secret Life of an American Art Forger) often claim that one of their primary motives, aside from the money, is to prove that the mavens of the art world aren't as expert as they claim to be.
With some much art around and so much money to be made selling it, art theft seems inevitable.
"Anything that's marketable can be stolen," says Edwin C. Schroeder, director of Yale University's Beinecke Rare Book and Manuscript Library in New Haven. He should know: in 2005, an incident at Beinecke uncovered an expert thief who confessed to stealing something like 100 rare maps from libraries and museums.
The thief's name is Edward Forbes Smiley III, a dealer in rare maps who was arrested at the Beinecke Library in June 2005 with three of Yale's maps in his possession. He was ordered to pay $2.3 million in restitution, helped identify where most of the maps ended up, and spent more than three years in prison.
Schroeder says the Smiley thefts (some claim he stole $100 million worth of rare maps over the years) "brought home again the importance of security" to all kinds of museums and libraries.
Like most museum and library directors, Schroeder won't talk specifics about the changes Yale made in the wake of the Smiley case. He says the security upgrades often involve a combination of responses involving technology, staffing and policy.
Another big issue for most institutions, he says, is money. "What can you afford to do?"
In major museums and libraries, there can be tens of thousands of pieces of valuable art, books, manuscripts, etc. The difficulty is preventing someone like Smiley, an expert with access to such collections, from walking out with stuff or substituting fakes.
"How do you verify… When do you check?" Schroeder says are the questions lots of security experts ask themselves every time another theft is discovered. He points out there's recently been "a whole other round of security upgrades" as a result of newly revealed thefts at historical societies in New York and Maryland.
In the past, it wasn't uncommon for embarrassed libraries and other institutions to keep quiet about thefts. Today, Schroeder says, "libraries [and museums, etc.] are more open," in part because they hope the legitimate arts and antiquities markets can help them recover the stolen items.
It's unlikely any sort of security would stop the kind of theft James Meyer allegedly committed.
He was the long-time assistant to Jasper Johns who was arrested in August and charged with stealing an estimated 22 works by the artist and selling them through a New York gallery. Meyer, who has pleaded not guilty, allegedly told gallery dealers Johns had given him the art works, and required that buyers keep the purchases secret for at least eight years.
Meyers' arrest shook up the Connecticut and New York art world, in large part because he'd been an assistant to Johns for 27 years. His well-known connection with Johns may have been the reason why the alleged thefts weren't discovered earlier.