The highlight on the pearl earring was applied using impasto, a technique in which paint is laid on thickly enough to retain a raised surface. Vermeer used this small buildup of light-colored paint to make the earring appear to catch a sharp glint.
Scientific examination has shown that the earring is not rendered with a detailed outline. Instead, Vermeer suggested its form with only a few economical marks: a bright highlight above and a softer reflection beneath, associated with the girl’s white collar. The thick highlight is especially important because the pearl itself is otherwise barely defined.
Impasto is different from glazing, which uses transparent or translucent layers to modify color and depth. Chiaroscuro describes strong contrasts between light and dark, while sfumato refers to softly blended transitions. Those terms may relate to broader artistic effects, but they do not name the raised paint used for this particular highlight.
The painting’s other surfaces were handled differently. The collar contains visibly textured impasto, whereas much of the turban was painted more thinly and smoothly, helping Vermeer distinguish fabric, skin, and reflective jewelry.