The diamond, weighing 709 carats, is now locked up in Sierra Leone's central bank in Freetown. It is one of the 20 largest diamonds ever found.
Here are the top five:
1. Cullinan Diamond, found in South Africa in 1905, weighed 3,107 carats
2. Lesedi La Rona, found in Botswana in 2015, weighed 1,111 carats
3. Excelsior Diamond, found in South Africa in 1893, weighed 995 carats
4. Star of Sierra Leone, found in Sierra Leone in 1972, weighed 969 carats
5. Incomparable Diamond, found in DR Congo in 1984, weighed 890 carats
Source: Mathew Nyaungwa, Rough and Polished