Panel a) and b): optical/NIR color-color diagrams of the 33 confirmed quasars. The respective symbols represent the individual selection method used to identify each quasar as defined by the legend. The yellow and red star symbols show the photometry of main-sequence and M-dwarf stars from the Hewett et al. (2006) catalog, respectively. Panel c): the reddening, A_V, of the confirmed quasars as a function of their color in g−r. The HAQs contribute to about half of the population of reddened quasars defined as having A_V> 0.1 (black dashed line).