The unnamed Lebanese man, 25, had swallowed the gems - worth an estimated £1.4 million - in an attempt to smuggle them out of the country.
He was detained by South Africa's elite 'Hawks' police unit as he was about to board a plane to Dubai at Johannesburg's O.R. Tambo International Airport.
A spokesperson for the airport said: "Our officers were tipped off about his activities and detained him at the airport. We nabbed him just before he went through the security checkpoint.
"We do not know whether he had swallowed the diamonds before he came to the airport or during arrest."
The suspected smuggler was given laxatives by officers to flush the diamonds out.
He is due to appear before a magistrate later today (November 15).
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