Synthetic diamond is a term used to describe diamond crystals produced by a technological process, as opposed to natural diamond, which is produced by geological processes.

Synthetic diamond is not the same as diamond-like carbon, DLC, which is amorphous hard carbon, or diamond simulants, which are made of other materials such as cubic zirconia or silicon carbide. The properties of synthetic diamond depend on the manufacturing process used to produce it, and can be inferior, similar or superior to those of natural diamond.

Unlike natural diamond which can occur in completely colorless form, most synthetic diamonds will have a slightly yellowish hue due to nitrogen impurities that are dispersed through out the crystal lattice structure during the growth phase. These impurities absorb the blue end of the light spectrum, making the stone appear yellowish.

Synthetic diamonds can be detected using infrared, ultraviolet, or X-ray spectroscopy, or by measuring UV fluorescence with a DiamondView tester.