The work by Ferrari and Robertson is centered on Raman spectroscopy. Diamond has the T2g 1332 cm -1 zone center mode, according to . The disordered graphite has two sharp peaks, G around 1580-1600 cm -1 and D around 1350 cm -1 , "usually assigned to zone center phonons of E2g symmetry and K-point phonons of A1g symmetry, respectively". And here, we find a fundamental observation made by Ferrari and Robertson: "The unusual fact is that G and D peaks, of varying intensity, position, and width, continue to dominate the Raman spectra of nanocrystalline and amorphous carbons, even those without widespread graphitic ordering".