MUMBAI (AFP) - Nirav Modi, who is under investigation for fraud, is a billionaire Indian jeweller whose extravagant diamonds have graced many Hollywood celebrities including Kate Winslet and Naomi Watts.

From stores in New York's Madison Avenue and Singapore's Marina Bay to the red carpet at the Oscars, Modi's luxury jewellery has long been popular with the rich and famous.

Hailing from a family of diamond merchants, the 47-year-old is one of India's richest men and is known for his love of Bentley cars and expensive Italian suits.

He is now also associated with serious fraud allegations.

Last month, Punjab National Bank (PNB) - India's second-biggest state-owned lender - approached the Central Bureau of Investigation alleging that Modi and members of his family defrauded it of 2.8 billion rupees (S$57.5 million).

PNB then said Wednesday (Feb 14) it had detected fraud of almost $1.8 billion at a single branch in Mumbai. The Press Trust of India news agency reported that the bank had made fresh allegations against Modi to the CBI.

On Thursday, Enforcement Directorate officers raided Modi's Mumbai home and other premises belonging to the jeweller.

Afterwards, PTI, citing officials, reported that Modi had left India in early January, before the bank detected either of the two fraud cases.

Modi, who was photographed alongside Indian Prime Minister Narendra Modi at the World Economic Forum in Davos last month, has not commented on the allegations. The two are not related.

Firestar Diamond has previously said the earlier case was not connected to the company.

Modi is the son and grandson of diamond traders. He was raised in Antwerp, Belgium and as a youngster dreamed of becoming a music conductor.

Rich list

But after dropping out of Wharton business school aged 19, he moved to India where he would find his calling producing diamond jewellery worth millions of dollars.

It was under the tutelage of his entrepreneurial uncle Mehul Choksi, the head of India's Gitanjali diamonds and now also caught up in the fraud storm, that Modi learned his trade.

In 1999, he founded Firestone - now called Firestar - a diamond giant currently boasting revenues of $2.3 billion.

He set up the eponymous Nirav Modi brand in 2010. The high-end chain has showrooms in some of the world's major cities, including London, Beijing and Hong Kong.

Watts was among several celebrities to attend the opening of the New York store in 2015.

The following year, Winslet wore a Nirav Modi bracelet, ring and earrings at the Oscars.

One of Modi's many career highlights was when one of his Golconda diamond necklaces sold for $3 million at a Christie's auction.

According to Forbes, Modi is worth $1.73 billion, placing him 85th on India's rich list.

Industry insiders say Modi's colourful persona belies his meticulous attention to detail. He is said to be involved in every part of the company, from jewellery design to production, to selecting store locations.

In an interview with Indian magazine Business World two years ago, he said he hoped to add around 30 Nirav Modi stores to the 17 that already exist by 2020.

Now his priority would appear to be fighting serious fraud allegations that have rattled India's corporate world.