For decades, Botswana’s diamonds have done something rare in the global economy: They turned a landlocked desert nation into one of Africa’s most stable and prosperous countries. Now the stones that financed that success are becoming the reason investors are uneasy. S&P Global Ratings affirmed Botswana’s long-term sovereign rating at BBB- and its short-term rating at A-3, preserving the country’s investment-grade status. But the agency kept the outlook negative, a warning that the rating could...





















