Studies carried out at the DTC Research Centre have shown that single-crystal CVD synthetic diamond is clearly distinguishable from natural diamond. This article presents information about the CVD process, the history of its development, the different kinds of CVD synthetic diamond material that can be produced, and properties that differentiate them from natural diamond. The authors studied more than a thousand CVD synthetic diamond samples that were grown for research purposes using a range of different process conditions. Absorption, photoluminescence, and cathodoluminescence spectra of these CVD synthetic diamond samples showed a range of different impurity-related features not seen in natural diamond. Photoluminescence imaging is also useful in identifying CVD synthetic diamond, and X-ray topography may give supportive evidence. The effectiveness of the Diamond Trading Company Diamond Verification Instruments for identifying CVD synthetic diamond is also described.