If you describe something or someone as a jewel, you mean that they are better, more beautiful, or more special than other similar things or than other people. Walk down Castle Street and admire our little jewel of a cathedral = gem
A bearing for a pivot a pivot in a watch, formed of a crystal or precious stone, as a ruby
A Synthetic material used to make a modern watch movement's bearings - These synthetic Rubies are almost as hard as diamonds The "Jewels" reduce friction and maintain the properties of the oil longer
To dress, adorn, deck, or supply with jewels, as a dress, a sword hilt, or a watch; to bespangle, as with jewels
If you refer to an achievement or thing as the jewel in someone's crown, you mean that it is considered to be their greatest achievement or the thing they can be most proud of. His achievement is astonishing and this book is the jewel in his crown
Bearing, endstone or pallet used for reducing friction Generally made of synthetic material, except for the precious or semi-precious stones (ruby, sapphire, garnet) which are sometimes used in "de luxe" watches
a precious or semiprecious stone incorporated into a piece of jewelry a person who is a brilliant and precious as a piece of jewelry
An ornament of dress usually made of a precious metal, and having enamel or precious stones as a part of its design
the term commonly used to refer to the screw-on pilot light lens on Fender guitar amplifiers These usually were red or green, but purple ones are purported to have real "mojo"