Can diamonds be made by man?

Yes they can and they are. Both natural and lab created diamonds have the same physical and chemical properties. Both have the same hardness, specific gravity, refractive index and dispersion; are polished using the same equipment and techniques; and have the same brilliance, sparkle, fire and scintillation. Both are also graded (cut, color, carat weight and clarity) using the same standards by the leading labs in the industry.

Yes, they coud be artificially made, but they are not of the same quality as the "natural" ones.