A heat sink comprises a heat sink body, a reflective layer disposed over the heat sink body that has reflectivity greater than 90% for light in the visible spectrum, and a light transmissive protective layer disposed over the reflective layer that is light transmissive for light in the visible spectrum. The heat sink body may comprise a structural heat sink body and a thermally conductive layer disposed over the structural heat sink body where the thermally conductive layer has higher thermal conductivity than the structural heat sink body and the reflective layer is disposed over the thermally conductive layer. A light emitting diode (LED)-based lamp comprises the aforesaid heat sink and an LED module secured with and in thermal communication with the heat sink. The LED-based lamp may have an A-line bulb configuration, or may comprise a directional lamp in which the heat sink defines a hollow light-collecting reflector.