Except for most blue diamonds, which are semiconductors, diamonds are good electrical insulators, meaning they reduce the flow of electricity. Blue diamonds owe their semi-conductive property to boron impurities, which act as a doping agent and cause p-type semiconductor behavior. Diamonds appear cold and hard, but they’re good conductors of heat because of the strong chemical bonds within the crystal.
Most natural blue diamonds contain boron atoms which replace carbon atoms in the crystal matrix, and also have high thermal conductivity. Heat is a property contained in most materials, and has the tendency to flow to areas of lesser heat. A substance that is a thermal insulator reduced the flow of heat.
Diamonds are actually excellent conductors of heat, better than more well-known heat conductors like copper or silver. Diamonds will warm-up. It’s as if when we talk about a diamond’s “fire,” it can refer to it figuratively as well as literally!
As much as we associate diamonds for their beauty and use as jewelry, only about 20% of all diamonds mined are gem-quality. The rest are good only for industrial uses. Because it’s the hardest substance, it’s used to cut other materials such as stone, metal and concrete. It’s also used to grind eyeglasses and computer chips.
Most industrial diamonds are mined, but scientists have successfully engineered synthetic industrial diamonds that have more versatile uses than mined diamonds. Now major companies like GE and even DeBeers make synthetic diamonds. The primary use for these synthetic industrial diamonds is to conduct heat away from devices that require a constant temperature for safe and proper operation.