Comparison of the r-band absolute magnitudes and r − i colours for the bumps seen in Type IIn SNe 2008aj, 2009ip (2012B event), and PTF10tel. Photometry and extinction corrections are taken from Hicken et al. (2017), Graham et al. (2014), and this paper, respectively. For clarity, colour data points with uncertainties > 0.1 mag are not shown. The vertical, dashed black line indicates the estimated start epoch of the light curve bumps.