  We use confocal microscopy to study an equilibrated crystal-liquid interface
in a colloidal suspension. Capillary waves roughen the surface, but locally the
intrinsic interface is sharply defined. We use local measurements of the
structure and dynamics to characterize the intrinsic interface, and different
measurements find slightly different widths of this interface. In terms of the
particle diameter $d$, this width is either $1.5d$ (based on structural
information) or $2.4d$ (based on dynamics), both not much larger than the
particle size. This work is the first direct experimental visualization of an
equilibrated crystal-liquid interface.
