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Jewel.

1. (Watchmaking.) A crystal or precious stone forming a bearing for the pivot of an arbor; especially used in watches.

The balance jewel always has an end-stone, or cap c, the balance running on the end of its pivot in order that it may have the utmost freedom; the pivot being but the 1/100 of an inch in diameter. Diamonds are sometimes used for end-stones, but rarely, if ever, for jewels, it being next to impossible to drill a hole sufficiently small in so hard a substance.

The invention of the process of drilling holes in rubies is attributed to M. Fazio, a native of Geneva, who introduced it into London in the year 1700.

Rubies are used as jewels in good watches. They are the hardest stone that can be drilled, but cheaper stones, such as crystals, garnets, etc., and even glass of hard quality, are often used.

The lower portion of Fig. 2717 represents on an enlarged scale the jeweled pivot-hole for the verge, or the axis of the balance of a marine chronometer. a is a hardened steel pivot, which is turned with a fine cylindrical neck, and is made convex at the end; the jewel consists of two stones; one b, usually sapphire or ruby, is convex above and concave beneath, of two different curvatures to thin it away in the middle, where the pivot-hole is drilled.

The other, c, called the top-stone or end-stone, is generally a ruby of plano-convex form, or else a diamond cut with facets. The flat side of this touches the end of the pivot.

The rubies or sapphires from which the jewels are made are sometimes split to the requisite thickness, but are commonly slit by a revolving iron disk charged with diamond-powder and oil. When sliced they are ground parallel on a flat plate of copper mounted on a lathe, into the face of which small fragments of diamond have been hammered, and afterwards polished on a similar plate with fine diamond-powder. They are afterwards turned circular and their edges beveled. In turning their faces to concave and convex form a fragment of diamond, mounted on a brass wire, is employed.

Drilling out the holes is also effected by a splinter of diamond mounted on a wire, this is usually accomplished at two operations, drilling into the two sides successively, after which the interior is polished with a fine steel wire and diamond-powder.

2. A precious stone; a gem. See gem-cutting; seal; diamond; Strass; doublet; brilliant, etc.

The proficiency of the ancient Egyptians in the ornamental arts is well shown in collections of Egyptian jewelry. One ancient collection, dating back to 1900 B. C., is in the possession of the Sultan, and comprises ear-rings, necklaces, seal-rings, and amulets. The workmanship is of the most beautiful description. Many handsome specimens are also in the Museum of the Historical Society of New York. The museums of Europe are rich in specimens from Phoenician, Egyptian, Etruscan, Greek, and Roman sources.

1877.

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