While overall room illumination is able to set the mood for a given space, the role of accent lighting is to create hotspots in the room that attract attention and enhance details that could otherwise go unnoticed. In the case of these luminaires, the diffusion and the light coming from above is given up to focused, directional light.
Rather than using diffusers, the luminaires aiming to provide accent lighting rely on reflectors and optics to provide a coherent beam of light that should focus on specific objects or spots in the room. It can blend with overall illumination and only provide extra boost of lighting to certain parts of the room, for example to accentuate highlights.
The other purpose can be a safety one, to attract attention to hazardous spaces or emergency exits. It can also be used in external applications, such as to spotlight certain parts of architecture: a tower clock, perhaps, or to accentuate gilding on a church tower.
For both interior and exterior purposes, colour can play an important part in a desired effect. The light source does not have to be an RGB LED light source, the colouring of the light beam can also be achieved by using coloured translucent filters, either glass or plastic ones. These can be interchangeable too, allowing for more dynamic effects. RGB LED gives the extra flexibility of changing the colour on the fly, creating dynamic effects of colour shifts.