Observed B − V color curve of SN 2014ab compared with those of three different SNe IIn subtypes. The reddening is corrected based on the values reported in the literature. The explosion date, i.e., day zero, for SN 2014ab is arbitrarily set to be 100 days before the optical discovery, or 46 days before the WISE first detection in the rest frame. The comparison sample including objects of the slowly-declining 1988Z-like subtype (solid lines) including SN 2010jl (Fransson et al. 2014), SN 2006tf (Smith et al. 2008), and SN 1988Z (Turatto et al. 1993), as well as the 1994W-like plateau subtype (dashed lines) including SN 1994W (Sollerman et al. 1998), SN 2009kn (Kankare et al. 2012), and SN 2011ht (Mauerhan et al. 2013), and finally, the prototypical rapidly-declining SN 1998S (dot-dashed line, Fassia et al. 2000).