But the business they bring lawyers, although lucrative, can be more mundane.
For Vanessa Havard-Williams, an environment partner at Linklaters & Alliance, which acts for mining clients including Anglo American and De Beers, and currently involved in a $17 billion deal to take De Beers private, diamonds, emeralds and rubies, like iron ore and coal, are things which have to be dug up cleanly and safely.
'In South Africa, a lot of the environmental issues are related to water use.
It is similar in South America and the US too,' she says.
Mines must not use too much of a scarce resource in those countries, or divert supplies away from others.
'There is also a risk with abandoned mines.
Some produce an acidic discharge, or there are structural issues, heave and subsidence,' she adds.
Mining and mineral extraction expertise within big City law firms tends to be pulled together in informal groupings, and will usually be gathered around corporate and banking partners.
Although the precious stones and metals might come out of the ground in Africa and Australia, the head offices are often in London, and so is the big legal business.
As well as De Beers, which is the dominant mining and wholesaleing company in diamonds, other big mining players Anglo American and Rio Tinto are both listed on the London Stock Exchange, and use UK law firms.
The City office of national firm Pinsent Curtis Biddle acted for South African firm Firestone Diamonds when it listed on the London Stock Exchange in 1998, and the same firm's Leeds office acts as Firestone's company secretary.
Firestone recently appointed London firm Reynolds Porter Chamberlain as its lawyers.
Ms Havard-Williams says that within Linklaters, 'we have developed sectoral interest groups, which are informal, and cut across the way we divide ourselves for organisational purposes'.
An example last year was when Linklaters advised Anglo American on the acquisition by a subsidiary of a privatised copper mines group in Zambia.
The team was led by corporate partners, but as well as environmental advice, other partners were brought in to advise on international arbitration, banking, power supply and project finance.
She worked with corporate partners when Anglo American moved its main stock market listing from Johannesburg to London three years ago.
Mining work can also spin into dispute resolution.
Three Norton Rose partners have been advising the Archangel Diamond Corporation on its interest in the Verkhotina deposit in the Arkhangelsk region and its relationship with its Russian joint venture partner, and the work has included representing the corporation in arbitration in Stockholm.
Rio Tinto's head of legal, Charles Lawton, says his group tends to use outside legal advice sparingly because it has a capable ex-City in-house team.
'For mining work, we generally don't employ those external firms in the UK.
When we do employ them it is for work such as litigation.
Also matters involving the public such as changes to our articles are always referred to external advisers,' he says.
'And of course when we're dealing with property in countries around the world we have good relationships with the local lawyers.'
The business dominating the thoughts of many of the top City corporate mining specialists this year certainly does demand external advisers - the proposal worth up to $17.6 billion which would take De Beers private, and end the cross-ownership between Anglo-American and De Beers.
It is lucrative legal business both because of the size of the amounts of money at stake, and because it is so complex.
It is crucial because De Beers is the axis around which the diamond business and its associated legal work revolves, the major player in mining and selling rough and cut stones.
As one lawyer says: 'We are all looking on to see how De Beers re-invents itself.'
De Beers currently mines more than 30 million carats of diamonds per annum from operations in South Africa, Botswana, Namibia and Tanzania, either directly or in partnership with a government.
This represents approximately 45% of the total value of the world's current production of natural diamonds.
De Beers also buys diamonds from Russia and Canada, and produces and sells natural and synthetic industrial diamonds.
In this latest deal, which illustrates the multi-national nature of much of the legal work connected to mining, Herbert Smith is advising De Beers.
The consortium which is in talks with De Beers about going private consists of: Anglo American, advised by Linklaters; Debswana Diamond Company, a joint venture between De Beers and the government of Botswana, advised by Ashurst Morris Crisp; and Central Holdings, the holding company of the Oppenheimer family, which is advised by Freshfields Bruckhaus Deringer, and by Maitland & Co.
De Beers ownership is of more than just financial interest to those running the business.
The US has long regarded De Beers as a near-monopoly because of its control of 70% of the gem diamond trade, and there is also an outstanding indictment against De Beers relating to industrial diamonds.
De Beers' directors cannot set foot in the US.
Linklaters has been among the law firms which have been trying to resolve the problem.
If diamonds and other precious minerals are similar to other mining deals at one end of the chain in legal terms, at the retail end, diamonds, precious metals and stones are closer in nature to designer luggage or designer clothes, as a brand with a brand value rather than an intrinsic worth.
Recognising this dichotomy, in January, De Beers announced a joint initiative with Moët Hennessy Louis Vuitton, the luxury products group, to establish an independently managed and operated company to develop the global consumer brand potential of the De Beers name.
As Joel Barry, a solicitor in the intellectual property department at Olswang, says: 'It is a very specialised market.
While experts have an enormous degree of expertise, the public usually only judge by size and shininess.
And probably the only brand most people know is De Beers, even though it is a mining company rather than a retail company.
Public perception is somewhat removed from contractual or legal reality.'
Often the legal work at this end of the precious stones and metals trade remains discreet.
Mr Barry says: 'We have done a lot of advertising work for jewellery companies, quite highbrow ones, quite a lot of high-end jewellery advice for household names.
A couple of disputes were disposed of quietly.'
One recent dispute which did reach the public domain, although it was settled out of court, was triggered when De Beers brought proceedings against the luxury goods firm Alfred Dunhill, over the rights to use of the word 'millennium' in 1999.
Niche intellectual property firm Willoughby & Partners represented Alfred Dunhill, which had presciently registered the brand 'millennium' for its watches and clocks, and Olswang represented De Beers, which was arguing that the word was too general to be trade marked, particularly at the turn of the millennium.
De Beers carried on using the name, but Dunhill kept its trademark.
Even the British Jewellers Association was concerned that the word 'millennium' had been registered to just one company and took legal advice from the mid-sized London firm Royds Treadwell.
Interestingly, for all the branding and acquisitions developments in the past 12 months, the biggest diamond and precious stones headlines last year came with not a corporate financier or intellectual property lawyer in sight.
They were generated by a gang attempting to steal £350 million worth of diamonds from the Millennium Dome's Money Zone, using a JCB digger.
The only solicitors involved on this are criminal ones, working on the prosecution and defence of the suspects.
Stephen Ward is a freelance journalist
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