Jewel cases are protective covers for compact discs, digital video discs, and similar optical media. The cases are designed to hold discs safely, preventing scratching or breakage. When the consumer needs to access the disc inside, the case is popped open and the disc is removed. There are a number of variations on the basic jewel case design which are intended to accommodate different needs.
There are three basic components of the case. The first is the cover, which is often clear. The cover has two arms with small bearings which fit into holes on a matching back piece, which is often made from colored or tinted plastic. The bearings and holes create a hinge which is sometimes compared to the precision jewel movement in fine watches. It is believed that this may be the origin of the name “jewel” case. Finally, an inserted panel in the back piece is designed to hold the disc in place, typically with a central toothed nubbin which grips the middle of the disc until the disc is gently pulled out or the nubbin is pressed to contract it, releasing the disc.
The design has two central weaknesses which can be irritating. The first is that the arms of the front cover are often surprisingly weak and brittle. If these cases are knocked about, the arms can break easily, and the bearings can be knocked off as well. The second is that the toothed nubbin in the middle of the case can break down over time, meaning that it will not secure the disc. As the disc rattles inside the jewel case, it can be severely damaged.
In many cases, optical media comes packaged in a jewel case to protect it. These cases are also used as decorative packaging and they may include artwork, information about the product inside, or other details which are designed to make them attractive as well as functional. Blank optical media may or may not come with jewel cases, and cases are also sold separately for repackaging.
The essential design of these cases is remarkably space efficient, since it fits a disc almost exactly. Slim-line models are even thinner than conventional cases, making it possible to fit more media in a smaller space. Many companies also manufacture cases designed to fit multiple discs, or cases with a space for an extra-large supplemental booklet. Since many musical recordings come with extensive notes, this extra space can be very useful, although it will cause the jewel case to take up more room on the shelf.