Speaking to ZBC News Police Spokesperson Superintendent Andrew Phiri said the suspect was under surveillance on the day he was arrested and was monitored from the point he left a certain house in Borrowdale until he was apprehended after a thorough search of his luggage at the airport.
It is believed that the suspect was housed at the house of a top Zanu PF politician.
The suspect is in police custody as investigations continue to ascertain whether the accused was working in connivance with other dealers.
The global diamond certification body ordered a ban on trade in diamonds from eastern Zimbabwe over concerns about human rights violations.
President of the World Federation of Diamond Bourses, Avi Paz said the decision to ban the Zimbabwe diamonds follows reports of violations of the Kimberly Process – a system meant to prevent trade in conflict diamonds.
The ban affects only the Marange deposits in eastern Zimbabwe, where local media have reported forced evictions of small-scale miners.
"The WFDB and its membership worldwide are committed to do all it can to prevent conflict diamonds from Zimbabwe or from any other source for that matter to be traded by our members," Paz said in a statement.
The group only allows its member bourses to trade in diamonds that are accompanied by a Kimberly Process certificate, meant to guarantee that the gems are not fuelling conflicts.
"Any bourse member who trades in rough diamonds without KP certification is liable for expulsion from his bourse, which in all practical terms means the exclusion from the entire diamond business community," Paz said.
Last year, Zimbabwean authorities sealed off an eastern mining area, where the state-run Zimbabwe Mining Development Corporation is now extracting up to 60 000 carats per week, according to official figures.