A Swiss luxury jeweller linked to Africa’s scandal-hit richest woman Isabel dos Santos has filed for bankruptcy.
De Grisogono is mainly owned by Angola’s state diamond firm and Mrs Dos Santos’s husband Sindika Dokolo.
Recently leaked documents show a loan to buy the jeweller is costing the Angolan government millions of dollars.
Ms Dos Santos denies allegations she enriched herself through corrupt deals when her father was Angola’s president.
José Eduardo dos Santos ruled Angola for 38 years until 2017. He controversially appointed his eldest daughter to head the state-owned oil firm Sonangol a year before he stood down.
Prosecutors are now seeking to recover $1bn (£760m) which they claim the 46-year-old billionaire and her associates allegedly owe the state.
They all deny any wrongdoing, saying the accusations are a politically motivated witch hunt.
Cannes Film Festival parties
A deal to buy Geneva-based De Grisogono, which creates diamond jewellery often worn by celebrities on the red carpet, was organised in 2012.
The BBC’s Panorama team, as well as other news outlets, published revelations – known as the “Luanda Leaks” – about the deal earlier this month, showing how it benefitted Ms Dos Santos’s husband.
The deal was supposed to be 50-50 partnership between him and Sodiam, Angola’s state diamond company.
But the documents show that 18 months after the deal, Sodiam had put $79m into the partnership, while Mr Dokolo had only invested $4m. Sodiam also awarded him a €5m success fee for brokering the deal, so he didn’t have to use any of his own money.
The documents reveal how Sodiam borrowed all the cash from a private bank in which Ms Dos Santos is the biggest shareholder.
Sodiam has to pay 9% interest and the loan was guaranteed by a presidential decree from her father, so the bank cannot lose out.
By the time Sodiam pays off the loans, it will have lost more than $200m, the firm’s chief executive told Panorama.
The Angolan government says the diamonds were sold at a knockdown price and sources told Panorama that almost $1bn might have been lost.
Mr Dokolo’s lawyers say he later invested $115m in De Grisogono and his company paid above the market rate for the raw diamonds.
When João Lourenço took over as Angola’s president in September 2017 he moved swiftly against the former first family, sacking Ms Dos Santos from Sonangol.
According to International Consortium of Investigative Journalists, it was at this time Sodiam sought to sell its stake in De Grisogono.
But no buyer could be found for the luxury brand, known for hosting parties at the Cannes Film Festival.
If the Swiss authorities accept any bid for bankruptcy by De Grisogono the firm says 65 employees will lose their jobs.
It was founded in the 1990s by Fawaz Gruosi, who made the brand famous with his bold and ornate designs.