Serasiya Milan Ramnikbhai, 30, pleaded guilty to a charge of theft with common intention and received his sentence Tuesday, according to Channel News Asia.

His accomplice, Mangroliya Manojkumar Kurjibha, 41, was handed the same jail term in July.

The duo entered Singapore on June 19 this year intending to steal the 4.95-carat diamond, valued at US$154,000 at the time, from Dianoche Diamonds Jewelry store in Chinatown.

They asked to view the gemstone at about 3 p.m., with Mangroliya distracting the sales manager by asking to see several items.

Serasiya spat out a fake diamond and switched it with the genuine gem before concealing the real stone in his mouth. His actions were captured on CCTV.

Mangroliya then told the sales manager he would consider the purchase before leaving with Serasiya.

The pair returned to their hotel and booked a flight to India departing that evening. However, the sales manager examined the fake gem and found that it was counterfeit, according The Straits Times.

The men were arrested at Changi Airport while trying to clear immigration. The genuine diamond was later recovered from Serasiya’s haversack.

The crime was carefully planned prior. The duo had commissioned a counterfeit diamond in India, made to match the targeted diamond’s specifications and serial number.

Serasiya’s lawyer, Amarick Gill, said Mangroliya devised the plan, sourced the counterfeit diamond, identified the trader Dianoche Diamonds Jewelry, and booked the flights and accommodation.

He also instructed Serasiya to conceal the fake diamond in his mouth and swap it for the genuine stone in exchange for money.

The prosecutor sought the same jail term imposed on Mangroliya based on the principle of parity. She said there was no material difference in their culpability to warrant an adjustment to Serasiya’s sentence.