We monitored the z = 0.158 quasar 3C 273 between 2015 and 2019 in the optical (BVrz) and near-infrared (JHK) with the aim to perform dust reverberation mapping. Accounting for host galaxy and accretion disk contributions, we obtained pure dust light curves in JHK. Cross correlations between the V band and the dust light curves yield an average rest-frame delay for the hot dust of tau(cent) similar to 410 days. This is a factor of two shorter than that expected from the the dust ring radius R-x similar to 900 lt-day reported from interferometric studies. The dust covering factor (CF) is about 8%, much smaller than that predicted from the half covering angle of 45 degrees found for active galactic nuclei (AGNs). We analyze the asymmetric shape of the correlation functions and explore whether an inclined biconical bowl-shaped dust torus geometry could bring these findings (tau(cent), R-x and CF) into a consistent picture. The hot varying dust emission originates from the edge of the bowl rim with a small covering angle 40 degrees < 45 degrees, and we see only the near side of the biconus. Such a dust gloriole with R-x = 900 200 lt-day and an inclination 12 degrees matches the data remarkably well. Comparing the results of 3C 273 with literature for less luminous AGN, we find a lag-luminosity relation tau proportional to L-alpha with alpha = 0.33-0.40, flatter than the widely adopted relation with alpha similar to 0.5. We address several explanations for the new lag-luminosity relation.