The world’s biggest producer of gem-quality diamonds holds presidential elections Friday. The same party has ruled the country since its independence.

Diamonds have been good to Botswana, but not everyone has benefited equally.

Diamonds helped transform Botswana from a very poor country into an upper-middle income economy. Former U.S. Ambassador Michelle Gavin says Botswana avoided the dreaded ‘resource curse.’

That’s when countries with rich natural resources experience low economic development. Gavin says Botswana largely protected its revenue.

“It hasn’t gone into Swiss bank accounts; it’s not in some former president’s yacht somewhere in the Mediterranean,” she says. “In Botswana, you can see what happened to those revenues. You can see it in the roads you drive on, the schools and the clinics that you pass.”

Botswana ranks high on the Ibrahim Index of African Governance. You still see poverty, though. And income inequality.

“There’s tremendous inequality and there has been for years in Botswana,” says political science professor Amy Poteete of Concordia University. “It’s one of the more inequitable countries in the world.”

Poteete says the volatility of diamond prices has increased in recent years, which plays into the country’s lower growth rates.

Whoever wins this presidential election will face continued pressure to diversify the nation’s economy.