Hardest mineral
Diamonds are the hardest mineral in the world. You can test if a diamond is real because a real diamond will scratch glass. They become much more valuable after they have been cut - made into a shape with many faces.
Diamond cutting takes place in very few places. In fact, almost all the diamonds in the world - around 92 per cent of them - are cut in one place. The place is called Surat and it is in Gujarat state in India.
Blood diamonds
In central Africa there are many problems. Different people are fighting for control. This part of Africa also has very valuable diamonds. When people buy diamonds from this part of the world, they help pay for more fighting. That's why these diamonds are called blood diamonds.
Where they come from
