What is "jewel block"

Jewel \Jew"el\ (j[=u]"[e^]l or j[udd]"[e^]l), n. [OE. juel, jowel, OF. jouel, juel, joiel, F. joyau, dim. of OF. joie joy, jewel, F. joie joy. See Joy.]

1. An ornament of dress usually made of a precious metal, and having enamel or precious stones as a part of its design.

   Plate of rare device, and jewels Of rich and exquisite form.
   --Shak.

2. A precious stone; a gem.
   --Shak.

3. An object regarded with special affection; a precious thing. ``Our prince (jewel of children).''
   --Shak.

4. A bearing for a pivot a pivot in a watch, formed of a crystal or precious stone, as a ruby.

   Jewel block (Naut.), block at the extremity of a yard, through which the halyard of a studding sail is rove.

n. (context nautical English) A block at the extremity of a yard, through which the halyard of a studding sail is rove.

A jewel block is a block on sailing ships through which the halliard is rove.

It is a single 7-inch block that is suspended from an eyebolt at the yardarm. It is the preferred term for the "studdingsail halliard block".