In this work, (100) oriented monocrystalline silicon samples were single point diamond turned under conditions that led to a ductile and brittle regime. Raman spectroscopy results showed that the ductile regime diamond turning of silicon surfaces induced amorphization and, on the contrary, in the brittle mode machining condition this amorphous layer does not exist. Ductile machined surface was found to be a mixture of crystalline and amorphous phases probed by (macro)-Raman spectroscopy. Transmission Electron Microscopy (TEM) analyses were then carried out in order to characterize the structural alteration in the machined surface and chips. The electron diffraction pattern of the machined surface detected a crystalline phase along with the amorphous silicon confirming the former results. The mechanism of material removal is widely discussed based upon the results presented here.