diamond

—diamondlike, adj.

/duy"meuhnd, duy"euh-/, n.

1. a pure or nearly pure, extremely hard form of carbon, naturally crystallized in the isometric system.

2. a piece of this stone.

3. a transparent, flawless or almost flawless piece of this stone, esp. when cut and polished, valued as a precious gem.

4. a ring or other piece of jewelry containing such a precious stone, esp. an engagement ring.

5. a piece of this stone used in a drill or cutting tool.

6. a tool provided with such an uncut stone, used for cutting glass.

7. crystallized carbon, or a piece of it, artificially produced.

8. an equilateral quadrilateral, esp. as placed with its diagonals vertical and horizontal; a lozenge or rhombus.

9. any rhombus-shaped figure or object oriented with its diagonals vertical and horizontal.

10. a red rhombus-shaped figure on a playing card.

11. a card of the suit bearing such figures.

12. diamonds, (used with a sing. or pl. v.) the suit so marked: Diamonds is trump. Diamonds are trump.

13. Baseball.

a. the space enclosed by home plate and the three bases; infield.

b. the entire playing field.

14. Print. a 4¹/₂-point type of a size between brilliant and pearl.

15. diamond in the rough, a person of fine character but lacking refined manners or graces.

adj.

16. made of or set with a diamond or diamonds.

17. having the shape of a diamond: a dress with a diamond print.

18. indicating the 75th, or sometimes the 60th, event of a series, as a wedding anniversary. See table under wedding anniversary.

v.t.

19. to adorn with or as if with diamonds.

[1275-1325; ME diamant < OF < VL *diamant-, s. of *diamas, perh. alter. of *adimas ( > F aimant magnet, OPr aziman diamond, magnet), for L adamas ADAMANT, diamond]

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I

Mineral composed of pure carbon, the hardest naturally occurring substance known and a valuable gemstone.

Diamonds are formed deep in the Earth by tremendous pressures and temperatures over long periods of time. In the crystal structure of diamond, each carbon atom is linked to four other, equidistant, carbon atoms. This tight crystal structure results in properties that are very different from those of graphite, the other common form of pure carbon. Diamonds vary from colourless to black and may be transparent, translucent, or opaque. Most gem diamonds are transparent and colourless or nearly so. Colourless or pale blue stones are most valued, but most gem diamonds are tinged with yellow. Because of their extreme hardness, diamonds have important industrial applications. Most industrial diamonds are gray or brown and are translucent or opaque. In the symbolism of gemstones, the diamond represents steadfast love and is the birthstone for April.

II

(as used in expressions)

Affair of the Diamond Necklace

Cullinan diamond

diamond cutting

Diamond Sutra

Diamond Cutter Perfection of Wisdom Sutra

Hope diamond

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▪ gemstone

  Diamond (gem) Diamond (gem)a mineral composed of pure carbon. It is the hardest naturally occurring substance known; it is also the most popular gemstone. Because of their extreme hardness, diamonds have a number of important industrial applications.

      The hardness, brilliance, and sparkle of diamonds make them unsurpassed as gems. In the symbolism of gemstones, the diamond represents steadfast love and is the birthstone for April. Diamond stones are weighed in carats (1 carat = 200 milligrams) and in points (1 point = 0.01 carat). In addition to gem-quality stones, several varieties of industrial diamonds occur, and synthetic diamonds have been produced on a commercial scale since 1960. See also industrial diamond; synthetic diamond.

  Diamonds are found in three types of deposits: alluvial gravels, glacial tills, and kimberlite pipes. Only in kimberlite pipes, such as those at Kimberley, S.Af., are they present in the original rock in which they were formed, probably lying at depths of more than about 75 miles (120 km). Diamonds found in alluvial and glacial gravels (till) must have been released by fluvial or glacial erosion of the kimberlite matrix and then redeposited in rivers or in glacial till.

      Diamonds vary from colourless to black, and they may be transparent, translucent, or opaque. Most diamonds used as gems are transparent and colourless or nearly so. Colourless or pale blue stones are most valued, but these are rare; most gem diamonds are tinged with yellow. A “fancy” diamond has a distinct body colour; red, blue, and green are rarest, and orange, violet, yellow, and yellowish green more common. Most industrial diamonds are gray or brown and are translucent or opaque, but better-quality industrial stones grade imperceptibly into poor quality gems. The colour of diamonds may be changed by exposure to intense radiation (as released in a nuclear reactor or by a particle accelerator) or by heat treatment.

      A very high refractive power gives the diamond its extraordinary brilliance. A properly cut diamond will return a greater amount of light to the eye of the observer than will a gem of lesser refractive power and will thus appear more brilliant. The high dispersion gives diamonds their fire, which is caused by the separation of white light into the colours of the spectrum as it passes through the stone.

      The scratch hardness of diamond is assigned the value of 10 on the Mohs scale (Mohs hardness) of hardness; corundum, the mineral next to diamond in hardness, is rated as 9. Actually, diamond is very much harder than corundum; if the Mohs scale were linear, diamond's value would be about 42. The hardness of a diamond varies significantly in different directions, causing cutting and polishing of some faces to be easier than others. For detailed physical properties, see native element (table).

      In the atomic structure of diamond, as determined by X-ray diffraction techniques, each carbon atom is linked to four equidistant neighbours throughout the crystal. This close-knit, dense, strongly bonded crystal structure yields diamond properties that differ greatly from those of graphite, native carbon's other form.

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