a precious stone, typically a single crystal or piece of a hard lustrous or translucent mineral cut into shape with flat facets or smoothed and polished for use as an ornament.
(usually jewels) an ornament or piece of jewellery containing a precious stone or stones:she loved dressing up in her jewelsthe Crown Jewels
a hard precious stone used as a bearing in a watch, compass, or other device.
a very pleasing or valued person or thing; a very fine example:she was a jewel of a nurse
the jewel in the (or one's) crown
the most valuable or successful part of something:Galway is the jewel in the crown of the Irish racing industry