From David Singer
Colin Finch’s theory on why CD jewel cases are so called is certainly imaginative and possibly even convincing, but sadly incorrect (19 June, p 31).
Jewel cases get their name from two small plastic bumps, or bearings, that the cover hinges on. The practice of using real jewels as bearings in watches and clocks is commonplace, and so all such bearings are termed jewels.
Quite why such a technical term was applied to the low-tech CD case is, perhaps, less obvious.
Cheltenham, Gloucestershire, UK
