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Abstract– None of the well-established nitrogen-related IR absorption bands, common in synthetic and terrestrial diamonds, have been identified in the presolar diamond spectra. In the carbonado diamond spectra, only the single nitrogen impurity (C center) is identified and the assignments of the rest of the nitrogen-related bands are still debated. It is speculated that the unidentified bands in the nitrogen absorption region are not induced by nitrogen, but rather by nitrogen-hydrides because in the interstellar environment, nitrogen reacts with hydrogen and forms NH+; NH; NH2; NH3. Among these hydrides, the electronic configuration of NH+ is the closest to carbon. Thus, this ionized nitrogen-mono-hydride is the best candidate to substitute carbon in the diamond structure. The bands of the substitutional NH+ defect are deduced by redshifting the irradiation-induced N+ bands due to the mass of the additional hydrogen. The six bands of the NH+ defects are identified in both the presolar and the carbonado diamond spectra. The new assignments identify all of the nitrogen-related bands in the spectra, indicating that presolar and carbonado diamonds contain only single nitrogen impurities.