Chemical Properties
Look at chemical properties of created and natural diamonds. They both have the same chemical properties: carbon. A diamond, created or natural, is a carbon allotrope, meaning that it a variant of the element carbon.
Physical Features
Both the created and natural diamond rate a hardness of 10 on the Mohs scale, a relative scale of hardness. Because both have the same crystal structure, the crystal cleavage is identical. The luster of the surface is also the same along with the specific gravity, refractive index and how light is dispersed.
Testing
The use of optical testing equipment (shortwave ultraviolet light, microscopy and spectroscopy) can expose the created diamond. Created diamonds have a perfect crystal structure, which has never been found in natural diamonds.
Considerations
In comparison of availability, fancy colored natural diamonds (more rare colors such as pink) are not as abundant as created diamonds. Created diamonds have also become more common on the market.