The diamond was snatched from a jewelry store in the northern Australian city of Cairns last weekend by a man who escaped on a bicycle.
Police were able to identify the suspect from closed - circuit TV and fingerprints left near the crime scene, and arrested a 29-year-old Briton yesterday as he attempted to board a flight to New Zealand from an airport in the southern city of Melbourne, Queensland state police said in a statement today.
"The X-rays are inconclusive at this time," Giles told ABC.
The man, identified by court records as Matthew Mark Luke Osborne, was to be extradited from Melbourne in Victoria state and appear in a Cairns court tomorrow charged with theft, police said.
The diamond's owner, Keith Bird, said police told him that the man had admitted stealing the diamond, and claimed to have swallowed it as he prepared to board the flight from Melbourne.
He said Western Australia state police had the suspect's fingerprints recorded for a traffic offence.
"If he thought he'd got away with it, why would you sit at the Melbourne airport and swallow it, and if you have to go to the loo on a flight to New Zealand? That would be a bit dangerous," Bird said.
"If he's not going to confess where the stone is, he's going to do some serious time," Bird added. Despite the hefty price tag, the diamond is only 0.31 carat with a diameter of 4.3 millimetres (11/64 of an inch). The value of pink diamonds from Australia's Argyle Diamond Mine is based more on colour than size.