Average spectra across the Diamond Ring. The [C II], ¹²CO and ¹³CO 1→0 line emissions, indicated with different colours, were averaged over a circular area of radius 8.3′ cantered on the Diamond Ring. The velocity range corresponding to the [C II] ring emission (−8 to 3 km s⁻¹) is marked the by vertical dashed lines (left). The peak emission of the ring is at −2.1 km s⁻¹, as determined by a Gaussian fit. The peaks at 7 kms⁻¹ and 15 km s⁻¹ correspond to Cl13 and the high-velocity gas, respectively Schneider et al. (2023).