Pure diamonds are pure carbon, although most diamonds contain some impurities. The presence of nitrogen causes the diamonds to absorb blue light, making the stones appear yellow. Boron is responsible for the blue-grey colouration of some diamonds. Hydrogen diamonds also appear blue, like 2-B diamonds, but are electrical insulators rather than semiconductors.
Properties of diamond
- Hardness
- Low coefficient of friction
- High thermal conductivity
- High electrical resistivity
- Low thermal expansion coefficient
- High strength
- Broad optical transparency from ultraviolet to infra-red
- Resistant to chemical corrosion
- Biologically compatible
