Diamond is the world's hardest naturally-occurring gemstone. Besides being used in jewelry, a diamond's toughness makes it ideal for use in tools.
Diamonds have many properties that make them unique. They are the most transparent material known to exist, and they conduct heat five times faster than copper. Diamonds can usually survive harsh environments that would normally destroy other stones, and diamonds can be used as a conductor or an insulator.
In modern times, synthetic (man-made) diamonds are often manufactured for use in telecommunications, windows, surgical tools and in microelectronic devices. Diamonds are often used in science and engineering because they easily withstand damage from radioactive and chemical forces.