Neptune's rings were first detected in star occultation experiments from Earth in 1983, but they were very difficult to study before the data from Voyager 2. The following image shows the faint rings of Neptune (the light from the body of the planet is blocked off in the black region to allow the rings to be seen clearly).

Only the two brightest rings show clearly in this image. Voyager 2 found additional fainter rings. The rings rotate in the same direction as the planet and are nearly in the equatorial plane.

The material in one of the rings is clumpy (more dense in some regions than others). This gave the impression in ground-based observations that the rings were arcs instead of complete rings, but the Voyager 2 data showed that they were complete rings. The rings of Neptune contain much more dust-size grains than the corresponding rings of Saturn and Uranus, and are quite narrow (about as narrow as the Saturn F-ring).

Information supplied by: http://csep10.phys.utk.edu