A diamond, made of pure carbon, is both a jewelry gemstone and a durable material in industry. There are two types of diamonds: gem diamonds and industrial diamonds.
The diamond is found in igneous rocks called kimberlite. It is a mineral composed of a chain of carbon atoms that have crystallized. Diamonds are sparkly gemstones used for adornment and are also the hardest naturally occurring substance with the highest thermal conductivity capability of any material.
Gem diamonds, used for jewelry and adornment, are highly reflective, giving them a sparkling shimmer. They can be translucent or opaque and can be many different colors ranging from clear to black. Diamonds can be very expensive. The quality and value of a diamond is based on its color, carat, clarity and cut. Most gem diamonds are clear or tinged with yellow, while pale blue diamonds are the most rare. Gem diamonds that come in different colors are called "fancy" diamonds and can be red, violet, green, blue and yellowish-green. The cut of a diamond can also increase the diamond's value. The best workmanship produces a perfect geometric shape with maximum luster.
Industrial diamonds are used as abrasives and for polishing, cutting and grinding because of their durability and heat-conducting properties. For example some oil drills have diamonds embedded in the metal of the drill bits to help cut through rocks during drilling.