It was a nod to the time couple had spent in Botswana in 2016, but the country is also famous for its diamonds. The world's second largest gem-quality diamond was found there in 2015
African countries are key players in the global diamond market, with diamond exports valued at $9.65 billion
The continent's diamond industry has been tainted by its association with "blood diamonds
," which are mined to fund conflict and civil war. The profits were used by warlords and rebels to buy arms during conflicts in Angola, the Democratic Republic of Congo and Liberia.
More recently, the Kimberley Process, which regulates the trade of rough diamonds, has been credited with reducing the problem, although NGOs including Global Witness have resigned from the Kimberley Process, saying it is ineffective.
Still, diamond exports are an important part of the economies of many African nations. Here are some of the top diamond-producing countries in Africa.
Once one of the world's poorest countries, Botswana quickly transformed into one of Africa's wealthiest
, partly because of diamond mining.
Diamonds were first mined in the country in 1967, and in 2016, Botswana produced over 20 million carats
. The mining sector now accounts for over $5.6 billion of the nation's export revenue.
Democratic Republic of Congo (DRC)
Africa's leading diamond producer by volume, DR Congo generated 23.2 million carats of diamonds in 2016. Much of that is generated by small-scale artisanal miners. The DRC Chamber of Mines estimates 200,000 to 400,000 people are employed in artisanal diamond mining.
Despite the large volume, the country's diamond exports are valued at just $229 million.
Angola is ranked as the third largest economy in sub-Saharan Africa and its diamond exports last year totaled over $1 billion
Although diamonds were first discovered in the country in 1912, a 27-year-civil war that ended in 2002 destroyed much of its infrastructure. During the war, much of Angola's diamonds deposits were used to fund armed conflict.
These days, although oil is much more important for Angola's economy, diamonds provide a significant additional export.
For more than a century and a half, diamonds have been mined in South Africa.
In 1888, Cecil Rhodes, established the country's first major diamond mine through his company De Beers
, the world's largest mining company.
In 2016, the country produced over 8.3 million carats
, with exports valued above $1.5 billion
Namibia is blessed with abundant diamond deposits. In 2016, the country produced over $915 million worth of diamonds. Mining as a whole provides more than half of the country's foreign exchange revenue.
In recent times, its supplies of terrestrial diamonds have dwindled, forcing it to look to marine mining. But the extra cost has reduced its profit margins.