HST colour as a function of galaxy redshift. The solid and dashed lines show the COSMOS library colours intrinsic and extended using Calzetti extinction law. While the library is composed with 31 models, we show two ellipticals (red-gold), one intermediate (green) and two starbursts (cyan-blue). The blue, green and red squares correspond to the observed colours of the spectroscopic redshift sample. The blue squares are the galaxies with good photometric redshift 2%(1 + z), the red squares are catastrophic outliers (> 15%(1 + z)) for which odds are higher than 90%. The green squares are the rest of the sample. The photo-z library colours match the colour of CLASH observations well.