Colours of J2140−0321 compared to those of other non-BAL quasars from SDSS-III at the same redshift. The arrows in the top right corner illustrate the estimates of colour excess due to H i, H₂, and dust (assuming SMC extinction law) at z_abs = 2.34. We note that because transmission is multiplicative, the corresponding magnitudes are additive and so are the colour vectors. The red arrow shows the estimated colour excess of J2140−0321 (circled red) due to the intervening ESDLA.For comparison, the colour excess that would produce a DLA with same column densities and reddening as those associated with GRB 080607 would reach the full ranges covered by both axes.