Diamond

The name Diamond comes from a Greek word adámas, meaning "unbreakable," "proper," or "unalterable". And that's exactly what diamonds are—unbreakable, unalterable, hard rocks. Diamonds mostly have no colour, but diamonds of different colours have been found. One of the most famous diamond, the Hope Diamond, is blue due to trace amounts of boron in the diamond.

Only about 20% of the diamonds mined have a clarity rating high enough for use as jewellery. The other 80% are relegated to industrial use. A lot of the time, the diamonds have small defects. If the piece is to be used for jewellery, often the best side of the diamond is chosen, and the jewellers try to cover up the not-so-nice spots (scratches, internal malformations, etc.) with the mounting metal.

Diamonds develop in the Earth's mantel under great pressure. They can be found between 140 and 190 km deep, but are even found at even 300 km occasionally. Diamonds need high temperatures to form. The correct temperature and pressure are only found under stable and thick parts of continental plates.

Often, diamonds are found around volcanoes. The huge up thrust of magma created in a volcano carries everything from the bottom to the top, so diamonds are often found in places like these.

Diamonds are found all over the world. Around forty-nine percent of diamonds are found in Central and Southern Africa. Diamonds from these places are sometimes called “blood diamonds”, because they were used to fund wars between nations and tribes. Diamonds are found other places, though. Canada, India, Russia, Brazil, US, and Australia are some of the many places.

Diamonds are used in many different ways. One ton out of every five tons of diamonds mined are used for jewellery. The rest of the diamonds used in industry. Synthetic diamonds are often used for drill bits and saws. Diamonds are used when precision is necessary, for example, they are used for fine engraving. Since diamonds are so hard, this makes it ideal for the job. Since diamonds can be used a lot, they are valuable.

http://en.wikipedia.org/wiki/Diamond_(gemstone)
http://en.wikipedia.org/wiki/Diamond
http://wanttoknowit.com/uses-of-diamonds/
http://library.thinkquest.org/26168/uses.html