synthetic diamond, man-made diamond that is usually produced by subjecting graphite to very high temperatures and pressures. Synthetic diamond resembles natural diamond in most fundamental properties, retaining the extreme hardness, broad transparency (when pure), high thermal conductivity, and high electrical resistivity for which diamond is highly prized.

- Brilliance diamond has extremely high reflectivity, its reflection critical angle is small, the range of total reflection is wide, light is prone to total reflection, and the amount of reflected light is large, thus producing high brightness.