Saudi Arabia and Thailand restored diplomatic ties 33 years after 4 Saudis were killed trying to recover $20 million in royal diamonds stolen by a Thai cleaner

• In 1989, a Thai cleaner stole $20 million worth of diamonds from a Saudi prince and fled the country.
• 3 Saudi diplomats and one businessman hunting the gems were killed, and the two countries cut diplomatic ties.

Saudi Arabia and Thailand reestablished diplomatic relations this week, more than 30 years after three Saudi diplomats were killed in a mission to recover diamonds stolen by a Saudi prince's Thai cleaner.

During a meeting on Wednesday, Thai Prime Minister Prayut Chan-ocha gave Crown Prince Mohammed bin Salman "his sincere regrets for the tragic cases that took place in Thailand between 1989 – 1990," the state-run Saudi Press Agency reported.

Riyadh cut ties with Thailand in 1989 after Kriangkrai Techamong stole diamonds worth $20 million from Prince Faisal bin Fahd al-Saud, the son of King Fahd, and shipped them to Thailand before fleeing.

Techamong sold the diamonds upon arriving in Thailand, and three Saudi diplomats based in Thailand were dispatched to track them down.

All three of the diplomats were killed in the process, and the perpetrators were never found.

Thai police were able to track down some of the diamonds, but when the Saudis examined them, they concluded most were fake. One of the stolen jewels, an extremely rare blue diamond, was never recovered, and gives the scandal its name: "The Blue Diamond Affair."

Shortly after, a Saudi businessman named Mohammed al-Ruwaili traveled to Thailand to investigate the theft, but he was also killed.

His killer was also never found, and Thai police have never convicted anyone for the four deaths.

In 1994, Mohammed Said Khoja, then-chargé d'affaires at the Saudi embassy in Bangkok said the four Saudi men had been "silenced."

Later, Thai police accused jeweler Santhi Sithanakan of buying the gems from Techamong and switching them with fakes. Sithanakan's wife and 14-year-old son were found dead soon after.

Chan-ocha told Crown Prince Mohammed on Wednesday that Thai officials were hoping for new information.

"Thai Prime Minister reaffirmed that Thailand had exerted utmost efforts to resolve the cases and that it stands ready to bring the cases to the consideration of the competent Thai authorities if new well-founded evidence relating to the cases should emerge," the Saudi Press Agency reported.

During the diplomatic freeze, Saudi Arabia canceled work permits for tens of thousands of Thai migrant workers, Reuters reported. The number of Thai workers in Saudi Arabia went from 150,000 to fewer than 10,000 in two years, the report said.