Linklaters and legal and wealth services firm Maitland have taken lead roles on a $5.1bn (£3.2bn) deal that will see the Oppenheimer family sell its stake in diamond company De Beers.

The deal, announced last week (4 November), will see mining company Anglo American buy the Oppenheimer family's 40% stake in De Beers – increasing its interest in the world's leading diamond company to up to 85%.

Linklaters is acting for Anglo American, fielding a team led by London corporate partners Michael Sullivan and Aisling Zarraga.

Maitland, meanwhile, is advising longstanding client the Oppenheimer family. The firm's Monaco-based chairman Michael Solomon is leading a team that also includes London corporate and commercial partner Rupert Weber, with managing director Steve Georgala advising on tax aspects.

The deal, which is expected to take up to a year to complete, will end the Oppenheimer family's 80-year ownership of De Beers.

Anglo American has been a major shareholder in the diamond company since 1926 and has been the company's largest shareholder since it became a private company in 2001 – a deal on which Maitland's Solomon also advised. Maitland also advised the Oppenheimer family in relation to the $1bn De Beers rights issue last year.

Solomon commented: "We have been the family's trusted advisers for many years and we are very pleased to be involved in a deal of this size and importance.

"Business has been surprisingly active despite all that has been going on in the euro zone. Private client work remains constant as there remains a lot of opportunities in the market for people with enough capital to take advantage of."

The Government of the Republic of Botswana also has rights to buy some of the Oppenheimer's interest and, should it exercise these right fully, this will leave Anglo American with a 75% stake.

Established in 1888, De Beers employs more than 16,000 people in more than 20 countries, with diamond mining operations in Botswana, Namibia, South Africa and Canada. As of 30 June 2011, De Beers had gross assets of $8.2bn (£5.1bn).