Nano-diamond as a diffuse ISM dust component (dashed-dotted): extinction (left) and emission (right). Inthis model it is assumed that 17 ppm of carbon is in the form of fully surface-hydrogenated, n-irradiated nano-diamonds (Jones 2022). For comparison the standard diffuse ISM THEMIS CM dust constituents (Jones et al. 2017) are also shown: a-C (dotted), a-C:H/a-C (dashed-triple-dotted) and a-Sil_Fe,FeS/a-C (long-dashed). The red lines shows the totals and the blue line (left) shows the E(B − V)-normalised extinction curve. These data were calculated using the DustEM tool (Compiègne et al. 2011).