Relation between the EW(CIII]) and C/O ratio as derived using HCM-UV. The red dashed line corresponds to the solar value. The cyan shaded region is the average C/O for Lyman-break galaxies in Shapley et al. (2003) and the red circle is the result for a composite spectrum of CIII]-emitters in Amorín et al. (2017). Individual CIII] emitters at high-z (red squares, Amorín et al. 2017) and low-z (black squares and circles, Berg et al. 2019a; Senchyna et al. 2021) are also included. Colors for our stacks are the same as in Fig. 13. The black dashed line is the best linear fit to our stacks, as displayed in Eq. (5).