Hertzsprung–Russell diagram built using only Gaia observable quantities (G, G_BP, G_RP, and parallaxes) for single WDs with G ≤ 20 obtained from Napiwotzki (2009), top, and GUMS, bottom. The Hertzsprung–Russell GUMS diagram considers discrete values for log g, which is reflected as quantised trends in this plot. SDSS WD samples extracted from Tremblay et al. (2011) and Kilic et al. (2010a) are overplotted with error bars as expected from Gaia observations. Table 2 shows that almost all SDSS WD plotted here have relative error of parallaxes better than 10%.