There's a lot of risk involved in passing off a fake or a forgery. If you're found out, your reputation can be irreparably damaged, or you could face prison. But people engage in the enterprise nonetheless, for artistic acceptance, ego gratification or for pure profit.

The terms "fake" and "forgery" are sometimes thought to mean the same thing, but there's a difference. A fake is an existing object that's been tampered with to create the illusion of greater value, and a forgery is an object fabricated in a familiar style to give the illusion of authenticity. But if you've paid a lot of money for something that's not what you thought it was, what's the difference?

The expert is the one thing standing between the fabricator and the victim. Experts will look at an intended purchase and verify its authenticity, thereby preventing a buyer from getting fleeced. But even experts get fooled, and when that happens, credibility earned through decades of hard work can be lost forever.

What follows is CNBC.com's list of 10 fakes and forgeries that fooled the experts. Read ahead and see what they are.

By Daniel Bukszpan
Posted 8 March 2012

The Amarna Princess was a statue created by British forger Shaun Greenhalgh in the style of ancient Egyptian art and sold for $661,000 to the Bolton Museum in Northern England in 2003. The statue was verified as a genuine, 3,300-year-old piece by both Christie's auction house and by the British Museum, according to BBC News.

The artist was investigated by Scotland Yard's Arts and Antiquities Unit, who found that he had been making forgeries for years, and using his kindly octogenarian parents to sell them. He admitted to money laundering and to selling faked and forged objects, and was sentenced to almost five years in prison.

Actor and comedian Steve Martin is an avid art collector. In 2004, he bought a 1915 painting by Dutch artist Heinrich Campendonk called "Landscape with Horses." Its authenticity had been confirmed by "a Campendonk expert," according to Der Spiegel, and Martin paid over $900,000 for it.

When he resold the work at Christie's in 2006 it fetched only $655,000. It was revealed to be a forgery by German painter Wolfgang Beltracchi, who admitted to forging the works of more than 50 artists. He was sentenced to a six-year prison term in 2011.

Han van Meegeren was a Dutch artist who forged a painting by Johannes Vermeer. He created a piece called "Christ and the Disciples at Emmaus," which was authenticated as a Vermeer by art historian Abraham Bredius and purchased by Rotterdam's Boijmans Gallery for $6 million.

After World War II, the painting was found in the collection of Nazi Field Marshal Hermann Goering. In order to avoid a lengthy prison sentence for colluding with the enemy, Van Meegeren was forced to confess to forgery. He was sentenced to a year imprisonment, but died of angina before he could begin his sentence.

The Brooklyn Museum is home to a large collection of Egyptian antiquities. It became the subject of controversy in 2008 when it was revealed that 10 of its 30 Coptic sculptures were 20th century fakes manipulated to look authentic. Byzantine scholar Gary Vikan told The Art Newspaper that the fakes originated from a village south of Cairo and have made their way to museums all over the world.

According to The Art Newspaper, this situation has arisen at other museums and was addressed by quietly removing the fakes and hoping no one would notice. The Brooklyn Museum, however, took the full disclosure route with its 2009 Coptic Sculpture Exhibit and explained the history of the collection on its website, describing the fakes as "modern impostors." The perpetrator has not been found.

More than four centuries after Sandro Botticelli's death, "Madonna of the Veil" surfaced and was attributed to the 15th- century Italian painter whose most famous work was "The Birth of Venus." It was lauded by the Medici Society and displayed by London's Courtauld Gallery in 1947, according to the National Gallery in London.

Former National Gallery director Kenneth Clark was skeptical of its origin, and further inspection revealed that elements used in the painting were not invented until hundreds of years after Botticelli's death. The painting is now accepted as a forgery by perpetrated by the late Umberto Giunti. It was displayed at the National Gallery in a 2010 exhibit called "Close Examination: Fakes, Mistakes and Discoveries."

In 1796, a play written by William Shakespeare was discovered. Or at least, that was what William Henry Ireland wanted people to believe. He was the son of an antiques collector, and he claimed that he had found it among his father's dusty curios. College of Heralds Secretary Francis Webb inspected it, concluding that the play came either from Shakespeare's pen, "or from Heaven."

In reality, the play was written by Ireland, but a theater producer agreed to give it its virgin performance before realizing what was going on. The producer eventually realized the play was a forgery prior to the premiere, and he was able to avoid billing it as a lost Shakespeare play before its first performance on April 2, 1796. The play was performed again for its comedic value in 2008 at Cambridge University.

Wilma Frances Minor was a writer who forged letters between President Abraham Lincoln and Ann Rutledge, the woman believed by some to have been his first love. They were published in serialized form in The Atlantic in 1928, and championed by people who knew the 16th president inside and out, including his own biographer Carl Sandburg.

Minor was paid $1,500 for the series (or over $20,000 today), according to The San Diego Union-Tribune, but after it was published, its authenticity was questioned and Minor eventually confessed. She explained that some of the interviews that formed the basis for the series were conducted by her clairvoyant mother during seances.

In 2007, Sen. Marcello Dell'Utri of Italy claimed that diaries belonging to the former dictator Benito Mussolini had been found. He said they had been verified by a handwriting expert, and Alessandra Mussolini, the dictator's granddaughter, had seen them.

Days later, the Italian weekly news publication L'Espresso reported that the diaries were fakes, citing historian Emilio Gentile. They had been presented to auction houses and newspapers several times in the past and were rejected as fakes at every turn. Among the giveaways were many historical errors, including an incorrect date for the dictator's own birthday. Dell'Utri is still in the senate.

In 1983, the German publication Stern published what it claimed was the first installment of the diaries of Adolf Hitler. According to reporter Gerd Heidemann, the diaries had been found in an East German hayloft after being rescued from a plane crash by a Nazi general. British historian Lord Dacre authenticated the find, and Stern paid almost $5 million for them, according to BBC News.

Two days after declaring them genuine, Lord Dacre walked back his endorsement at a news conference. The diaries were revealed to be forgeries after another expert found that the paper, glue and ink used were not in use until after World War II. They were ultimately found to be the work of Konrad Kujau, who was imprisoned for the crime, but when he was released, he traded on his fame by selling his own forged paintings. He died in 2000, but his forgeries can still be seen on the Internet.

Tatiana Khan was the owner of the Chateau Allegre gallery in Los Angeles. She sold what was purported to be a $5 million 1901 Picasso painting called "The Woman in the Blue Hat" to a customer for only $2 million. After the purchase, the customer contacted On-Line Picasso Project Director Enrique Mallen to see the painting, but Mallen had to break it to the customer that the painting was a fake.

Although she initially put up some resistance, Khan ultimately pleaded guilty to making false statements to the FBI and to witness tampering. She also admitted that the painting was a fake which she had paid an art restorer $1,000 to create. She was sentenced to five years' probation, according to The New York Times.