We demonstrate multi-scale multi-parameter optical coherence tomography (OCT) imaging and visualization of Johannes Vermeer's painting Girl with a Pearl Earring. We perform OCT imaging at the scale of an entire painting with micrometer axial and lateral resolution, which makes it possible to observe the painting over more than 5 orders of length scale. From the multi-scale OCT data we quantify multiple parameters in a fully automated way: the surface location, the scattering strength, and the (glaze+varnish) layer thickness. In the multi-parameter OCT data of Girl with a Pearl Earring we identify various features: Vermeer's brushstrokes, surface craquelure, paint losses, and restorations. Through an interactive visualization of the Girl, based on the OCT data and the optical paint properties of historical reconstructions of Vermeer's paint, we can virtually study the effect of the lighting condition, viewing angle, zoom level and presence/absence of glaze layer. The interactive visualization demonstrates various new painting features. Moreover, it shows that the glaze layer structure and its optical properties were essential to Vermeer to create an extremely strong light to dark contrast between the figure and the background, which gives the painting such an iconic aesthetic appeal.