Five Filipinos were arrested with a diamond necklace reported stolen from a jewellery fair in Bangkok shortly before boarding a flight at Don Mueang airport.
The three men and two women, believed to work together as a gang, were apprehended late on Wednesday night, said Pol Maj Gen Surachet Hakphan, commander of the Tourist Police Division.
Tourist police based at the airport found a diamond necklace worth about 300,000 baht in a bag belonging to one of them.
The arrest followed a complaint to police by a gem trader with a booth at the 58th Bangkok Gems and Jewellery Fair in Muang Thong Thani, Nonthaburi.
Paramin Taharian told police that two foreigners, possibly Filipinos, claiming to be a mother and son had arrived at his booth about 2pm. The son asked to see two pairs of diamond earrings, saying he wanted to buy a pair for his mother.
The woman caused a distraction by starting a conversation with him, Mr Paramin said
He believed this was when the man took the opportunity to snatch a diamond necklace from the showcase. The pair did not buy anything and quickly left the booth.
Mr Paramin said he was unaware of the missing necklace at the time because it was not among the items he showed them. Instead, they took it from a showcase.
He noticed the missing necklace only when checking his inventory later, about 6pm, and immediately contacted police, said Pol Maj Gen Surachet.
Tourist police alerted airport officials at Suvarnabhumi and Don Mueang airport to watch for the two suspects, sending them a video from a surveillance camera at the fair.
Officials at Don Mueang spotted the duo around 10pm in the company of three other Filipinos in a departure lounge waiting to catch a flight to Phuket, and eventually to Manila.
They were approached and asked to allow a search. A search of their luggage revealed a diamond necklace matching the item reported stolen, along with some other jewellery.
Pol Maj Gen Surachet said police investigators believed the five suspects were an organised gang of thieves. They were being held in custody at Pak Kret police station pending further investigation.
All were then detained for further questioning.
The suspects were identified as Ebueza Christian Carpio, 27, Bien Nonoy Mulobuko 27, Chapoco Florenz Velarde, 65, and the two women, Canoy Adoration Carpio, 58, and Mallari Sofia, 56,
Tourist police said the five arrived together on Sept 5 and had booked a return flight to Manila on Sept 12.