Colour–colour diagram of the observed‐frame SPIRE fluxes. The plot is divided into five redshift bins, in which the data from that bin are plotted along with the colours expected from various models as they would be observed at the median redshift in the bin. Data are divided into the three g−r colour bins, denoted by symbols and colours, and six M_r bins denoted by the size of the data point (larger = brighter). Data points and error bars in the red bins include the lensing correction and its uncertainty. Three families of models are shown: two consist of isothermal SEDs with either β= 1 or 2, and various dust temperatures; the third is a two‐component SED with β= 2, warm dust temperature T_w= 30 K, with a cold‐to‐hot dust ratio of 100. Each model is given a range of (cold) dust temperatures; the dots along the lines indicate 1 K increments from 10 K (lower left‐hand side) to 30 K. Choosing a single‐component model with β= 2 leads to a range of temperatures between 13 and 22 K.