(FORTUNE Magazine) – Nelson Mandela can claim to be a patriot and peacemaker in South Africa, but he's also a pretty good market mover. Since the president of the African National Congress called for an end to economic sanctions against his country last September, shares on the Johannesburg Stock Exchange (JSE) -- among the world's ten largest -- have risen a hardy 31%. If South Africa's first one- man, one-vote elections occur on April 27 without a major calamity, the market should continue its ascent, though there will be periods of volatility before then. Says Richard Stuart, research director of Martin & Co., a Johannesburg brokerage: ''We've been cut off from the world for so long that there's a tremendous amount of energy being released in the markets.'' You can buy most of these stocks directly by having your broker execute the transaction through a South African broker. Some also trade as ADRs on Nasdaq. But you should first familiarize yourself with an economy loaded with oddities. Under the nation's dual-currency system, the so-called financial rand that foreign investors use to buy stocks and bonds is discounted by 21% relative to the commercial rand used by South Africans. That means a run-up can prove more lucrative for outsiders than for locals. An additional payoff waits for nonresidents if -- as is widely predicted -- the system is scrapped and the two currencies are equalized. - More quirks: Nobody quite knows whether to treat the market as emerging, warranting the sky-high P/E multiples of, say, Malaysia, or as a developed market like those of New York or London (calculated in commercial rands, the JSE trades at 18.5 times trailing earnings, and 14.6 times in financial rands, compared with 23 times for New York and about 40 for Malaysia). So where should investors mine for riches? Bond seekers may want to consider government issues or those of the state electric utility, Eskom. Though inflation has fallen from 16% into single digits over the past two years, many yield about 14.5%, including the boost you get from buying in financial rands. Equity may hold more allure. After sanctions, recession, and a crippling drought, many South African companies are as lean as gazelles and ready to prosper during an economic rebound. Start by taking a look at the handful of conglomerates that through a mind-boggling series of cross holdings control more than 80% of the value of the Johannesburg exchange. Because of those seemingly endless numbers of subsidiaries and investments, these conglomerates give investors a broad cross section of the market, like mutual funds. South Africa's most heavily capitalized company, Anglo American, is one example. The world's biggest gold producer, it also owns 33% of De Beers Consolidated Mines, the diamond monopoly that should benefit from swelling demand for gems as the world economy recovers. Anglo has big investments in steel, construction, and insurance too. Says John Morris of brokerage Davis Borkum Hare & Co. in Johannesburg: ''You're really buying South Africa Inc. when you buy Anglo.'' The ADR traded recently at $46.63, or 12 times Morris's per share earnings estimates for the fiscal year ending in March 1995. As for De Beers, whose ADR recently traded at $25.63, he expects earnings to rise 16% this year, to $2.46 per ADR. Two infrastructure plays are Reunert, which makes telecommunications equipment and electricity meters, and Murray & Roberts, a heavy-constuction company. Analyst Michael Spriggs of S.G. Warburg Securities in London figures Reunert will benefit from efforts to bring power to more black townships. He expects Reunert shares to rise as much as 66%, to $5.80 by the end of 1994. Spriggs thinks Murray & Roberts ($16.20) is a longer-term investment. All that construction work is bound to produce some powerful thirsts. When it comes to beer, South Africans brew oceans of it, more than 90% by South African Breweries. It can turn a profit on six-packs costing as little as $2.50. Says Kevin Jacobs, a director at Silvis Barnard Jacobs Mellet & Co. in Johannesburg: ''Nobody can hope to compete with them.'' The company also owns a department store chain. Jacobs expects the shares to rise 21% to $25 this year. Food companies are another good bet. Analyst Maurice Onyuka of money manager Clemente Capital in New York City expects shares of Tiger Oats, a leading corn and flour miller, to rise 26%, to $14.60 this year, and those of Tongaat-Hulett, a sugar processor, to rise 28%, to $8.60. Closed-end mutual funds by Morgan Stanley and Alliance Capital are in registration. But the best way to get diversity now may be Liblife Strategic Investments, or Libsil, an investment portfolio controlled by Liberty Life Association of Africa. Says Peter Jardine of Saicor Securities in New York City: ''It's like getting 3 1/2 blue chips in one shot.'' Libsil ($3.12) owns stakes in Standard Bank Investment; South African Breweries; Premier, a food company; and Gold Fields of South Africa, a mining outfit.

CHART: NOT AVAILABLE CREDIT: R. KLEIN FOR FORTUNE CAPTION: JOHANNESBURG STOCK EXCHANGE The stock market has risen 31% since Mandela declared an end to sanctions.