High quality reflectance coatings

A multiple-pane insulating glazing unit that includes a first pane and a second pane, the multiple-pane insulating glazing unit having at least one between-pane space, the first pane having an interior surface that is exposed to a between-pane space of the multiple-pane insulating glazing unit and that bears a low-emissivity coating having at least three infrared-reflection film regions each comprising silver, such that the low-emissivity coating comprises a first transparent dielectric film region, a first infrared-reflection film region, a second transparent dielectric film region, a second infrared-reflection film region, a third transparent dielectric film region, a third infrared-reflection film region, and a fourth transparent dielectric film region, each of said three infrared-reflection film regions being in direct contact with overlying dielectric film that is deposited as dielectric film throughout its thickness and thus is devoid of an innermost metal portion, the multiple-pane insulating glazing unit having a visible-thermal efficiency ratio of greater than 2.3, the visible-thermal efficiency ratio being defined as visible transmittance divided by solar heat gain coefficient, the low-emissivity coating including three or more optical cavities, each of the three or more optical cavities having a thickness of between about 300 Å and about 850 Å.