One more fact that might be interesting about natural diamonds: not all of them are extracted by digging mines; the oldest way of extracting diamonds is by sifting through alluvial deposits.

This method originated centuries ago in India. In fact, until the 18th century, this was the only known method. The most famous origin of alluvial diamonds is the Godavari-Krishna river delta in the old Golconda Sultanate. This particular site was exhausted about 200 years ago, making Golconda diamonds especially precious now.