Ly Thi Ngoc Bich, 45, and Nguyen Thi Linh, 52, were held Monday as local police expanded their investigation into Prajapati Shaileshkumar Hareshbhai, who was arrested at Tan Son Nhat International Airport on Oct. 23.
He was found with a metal box containing over 700 diamonds, both natural and lab-grown, when arriving from India.
He confessed to the police he had intended to sell them to local stores.
The police found Linh had links with him and had gone into hiding after his arrest. Investigators have not revealed what their connection is.
She also tried to find some way to evade punishment, and was introduced to Bich.
Bich agreed to help both her and Hareshbhai "escape" punishment or at least receive a reduced sentence by using her connections with some officials.
She received VND1.2 billion (US$47,300) from Linh and paid a lawyer VND150 million to assist her but kept the rest despite not fulfilling her commitment.
The police investigation continues.