Art of deception: Crystal skulls in British, US museums were fakes wrote:How about this for the next instalment of the Indy franchise: "Indiana Jones and the Dodgy Antiques Dealer"?

Less than three months after the Quai Branly Museum in Paris discovered that a crystal skull once proclaimed as a mystical Aztec masterpiece was a fake, it is now the turn of the British Museum and the Smithsonian Institution to find they were victims of skull-duggery.

Scientists from those two prestigious institutions on Wednesday said their crystal skulls were cut, honed and polished by tools of the industrial age, not by Mesoamerican craftsmen of yore.

"The skulls under consideration are not pre-Columbian. They must surely be regarded as of relatively modern manufacture," they say.

"Each skull was probably worked not more than a decade before it was first offered for sale."

The skulls became star exhibits in all three museums long before the Indiana Jones movie, "The Kingdom of the Crystal Skull," hit the movie screens this year.

The superstitious deemed them part of a collection of 12 skulls, endowed with healing or mystical powers, that dated back to the ancient culture of Central America.

Reuniting all 12 skulls, together with a putative 13th, would conjure up a massive power that would prevent the Earth from tipping over on December 21 2012, the "doomsday" in the Mayan calendar, according to one fable.

Legend-lovers had a bad day on April 18 when the Quai Branly said it had found grooves and perforations in its 11-centimetre (4.4-inch) -high quartz skull revealing the use of "jewellery burrs and other modern tools."

Doubts had also surfaced about the skulls in London and Washington, with art experts noting they were unusually large and with teeth markings that were exceptionally linear.

Seeking the verdict of science, researchers from those two museums examined the skulls with electron microscopes, looking at tiny scratches and marks left by the carving implements.

These were then compared with the surfaces of a crystal goblet, rock crystal beads and dozens of greenstone jewels known to be of genuine Aztec or Mixtec origin.

The study appears in the Journal of Archaeological Science, published by the Elsevier group.

The skull in the British Museum, purchased in 1897, is made of transparent rock crystal and is 15 centimetres (six inches) high. The Smithsonian skull, acquired by the museum in 1992, is of white quartz and measures 25.5 cms (10 inches) in height.

The investigators found that rotary wheels gave the British skull its sharp definition, a drill had dug out the nostrils and eyes, and diamond or corondum had been applied with iron or steel tools to smooth its upper surfaces.

As for the US skull, "faint traces" of tool marks remain, but these too are consistent with rotary wheels or grinding pads, the authors say.

No evidence has ever been found that rotary wheels were used to cut stones in Central America before the arrival of Europeans.

The investigators also found a black-and-red deposit in a tiny cavity of the Smithsonian skull. X-ray diffraction showed it to be silicon carbide -- a tough compound that only exists naturally in meteorites but is widespread in modern industrial abrasives.

Tiny irregularities in the quartz suggest the mineral for the London skull came from the European Alps, Brazil or Madagascar, while the quartz for the Washington skull had "many potential sources," including Mexico and the United States.

The sleuths pored over the archives of both museums, the Museum of Mankind in Paris, the French National Library, the Hispanic Society of America and newspaper records in a bid to find where the skulls came from.

The only documentation existing for the Smithsonian skull indicates it had been purchased in Mexico City in 1960. The scientists believe the skull was "probably manufactured shortly before it was purchased" there.

As for the British Museum and Quai Branly skulls, the paper trail leads to a French antiques collector by the name of Eugene Boban Duverge.

Boban had a shop in Mexico City and parlayed his way to the salons of Paris thanks to the 1863-67 "French Intervention," when troops of France's Second Empire invaded Mexico.

He built up a collection of 2,000 pre-Columbian artefacts, the biggest in Europe at the time. It included several crystal skulls, including the newly-unmasked fakes in London and Paris.

The skull that would eventually be bought by the British Museum was acquired by Boban between 1878 and 1881, possibly in Europe, the study says. In 1885, he tried to sell it to the National Museum of Mexico, but was turned down.

A year later, Boban sold it an auction to the New York jeweller's Tiffany's.

Two years later, Tiffany's sold the skull to a Californian businessman who nearly a decade later went bust and asked the jeweller to hunt for a new buyer.

So it was that Tiffany's vice president, George Kunz, made a pitch to the British Museum.

He recommended the purchase of "this remarkable object," sketched a past of colourful ownership, beginning with a Spanish soldier who had brought it back from Mexico, and quoting the opinion of others that the skull was of ancient Mexican origin but no-one knew for sure.

The rest, as they say, belongs to history... and human gullibility.