Why are diamonds expensive?

Diamonds are very expensive because they occur at relatively few places in the world – like Russia and South Africa – and are very difficult to extract. They are made of carbon and are the hardest substance known to us, which is the result of the high pressure at their place of origin deep below the Earth’s surface. They are naturally thrown up on the Earth’s surface through volcanic eruptions. For this reason they are mined in the vents of the extinct volcanoes. Being very hard they have great industrial use for grinding tools. Diamonds can also be made artificially by creating the same conditions as found under the surface of the Earth, but these artificially made diamonds are not as valuable as natural diamonds.