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How do you know that bottle of extra-virgin Italian olive oil you just picked up from the corner market is the real thing? Problem is, you probably don’t, because fake olive oil is rampant.

Now, Swiss researchers have come up with a solution that they say could put olive oil fraudsters out of business.

A team at ETH Zurich’s Functional Materials Laboratory has developed an “invisible oil tag” that can be added in miniscule amounts to pure olive oil, making it virtually impossible for crooks to counterfeit or adulterate the pure product without being detected.

A person holds a bottle of olive oil. Fake olive oil that's passed off as the pure stuff is a big business.Michelle Locke / AP file

The marker is made up of tiny magnetic DNA particles encapsulated in a silica casing. Just a few grams of it are enough to “tag the entire olive oil production of Italy,” the researchers say. Suspect counterfeiting? Just extract and analyze the marker particles. “If the concentration of nanoparticles does not match the original value, other oil – presumably substandard – must have been added,” the researchers add.

“The method is equivalent to a label that cannot be removed,” Robert Grass, lecturer in the Department of Chemistry and Applied Biosciences at ETH Zurich, said in a statement.

Grass told NBC news via email that the marker is safe, cheap to produce and can easily be added to every bottle of Italian olive oil shipped to the U.S. “Very, very easy … just add one microgram (a millionth of a gram) of our tracer per liter of oil to the product prior to shipping,” he said.

Moreover, the taste of the oil would not be affected.

The research, “Magnetically Recoverable, Thermostable, Hydrophobic DNA/Silica Encapsulates and Their Application as Invisible Oil Tags,” was recently published in the journal ACS Nano.

A forgery-proof label could go a long way toward stamping out olive oil counterfeiting, a multibillion-dollar racket where the product is either diluted with cheaper oils and passed off as pure, or declared to be from someplace where it’s not.

A 2010 study by UC Davis researchers found that 69 percent of the imported olive oils they sampled are not the top-grade “extra virgin” oils that their labels claim they are. Counterfeit olive oil was also the topic of a 2011 book, "Extra Virginity: The Sublime and Scandalous World of Olive Oil," by Tom Mueller.