Disclosed is a combinatorial synthesis of Diamond wherein a first reactive species is produced by catalytic treatment of Acetylene, a second reactive species is produced by decomposition of a hydrocarbon source having a low Hydrogen-to-Carbon ratio using a high energy discharge, and the two reactive species so obtained are combined in the vapor phase to yield Diamond without the need of post-treatments. The reaction is efficient and affords Diamond under mild conditions with high purity such that it may be useful for producing Diamond for semiconductor and microelectronics applications.