The friends dug up the 15.34-carat gem-quality diamond in central India.
Whistleblower reported diamond retailer “Vashi” to the Serious Fraud Office a year before it collapsed.
Botswana's diamond-reliant economy is under strain - the main diamond company saw a 50% drop in sales last year.
Insiders tell BBC Panorama how the man behind upmarket jeweller Vashi conned investors and customers.
BBC correspondents visit export hubs across India to assess how steep US tariffs are impacting business owners.
Botswana, one of the world's biggest diamond producers, has been struck by a global decline in the market.
Socialite Virginia Courtauld's diamond-encrusted brooches are going on display at Eltham Palace.
Not all jewellers are sold on man-made diamonds, which can be grown in a matter of days.
In Panna, families hunt for diamonds hoping to strike rich and escape the cycle of poverty.
