Diamond

Town in Newton County, southwest Missouri; population (1990) 800. It is situated 19 km/12 mi southeast of Joplin. George Washington Carver, the noted scientist long associated with Alabama's Tuskegee Institute, was born here. His home, to the southwest of the town, is now part of the George Washington Carver National Monument.


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Experiments

Using a device known as a diamond-anvil cell, a moderate force applied to the small tips of two opposing diamonds can be used to attain extreme pressures of millions of atmospheres or more, allowing scientists to subject small amounts of material to conditions that exist deep within planet interiors.

In 1999 US scientists turned a diamond into a metal using a very powerful laser to compress it.

Cutting

Rough diamonds are often dull or greasy before being polished; around 50% are considered ‘cuttable’ (all or part of the diamond may be set into jewellery). Gem diamonds are valued by weight (carat), cut (highlighting the stone's optical properties), colour, and clarity (on a scale from internally flawless to having a large inclusion clearly visible to the naked eye). They are sawn and polished using a mixture of oil and diamond powder. The two most popular cuts are the brilliant, for thicker stones, and the marquise, for shallower ones. India is the world's chief cutting centre.

Noted rough diamonds include the Cullinan, or Star of Africa (3,106 carats, over 500 g/17.5 oz before cutting, South Africa, 1905); Excelsior (995.2 carats, South Africa, 1893); and Star of Sierra Leone (968.9 carats, Yengema, 1972).

Practical uses

Because diamonds act as perfectly transparent windows and do not absorb infrared radiation, they were used aboard NASA space probes to Venus in 1978. The tungsten carbide tools used in steel mills are cut with industrial diamond tools.

Varieties

There are four chief varieties of diamond: well-crystallized transparent stones, colourless or only slightly tinted, valued as gems; boart, poorly crystallized or inferior diamonds; balas, an industrial variety, extremely hard and tough; and carbonado, or industrial diamond, also called black diamond or carbon, which is opaque, black or grey, and very tough. Industrial diamonds are also produced synthetically from graphite. Some synthetic diamonds conduct heat 50% more efficiently than natural diamonds and are five times greater in strength. This is a great advantage in their use to disperse heat in electronic and telecommunication devices and in the production of laser components.

Sources

Diamonds may be found as alluvial diamonds on or close to the Earth's surface in riverbeds or dried watercourses; on the sea bottom (off southwest Africa); or, more commonly, in diamond-bearing volcanic pipes composed of ‘blue ground’, kimberlite or lamproite, where the original matrix has penetrated the Earth's crust from great depths. They are sorted from the residue of crushed ground by X-ray and other recovery methods

History

Diamonds were known before 3000 BC and until their discovery in Brazil in 1725, India was the principal source of supply. Present sources are Australia, the Democratic Republic of Congo (formerly Zaire), Botswana, Russia (Yakut), South Africa, Namibia, and Angola; the first two produce large volumes of industrial diamonds. Today, about 80% of the world's rough gem diamonds are sold through the De Beers Central Selling Organization in London.

diamond

Generally colourless, transparent mineral, an allotrope of carbon. It is regarded as a precious gemstone, and is the hardest substance known (10 on the Mohs scale). Industrial diamonds, which may be natural or synthetic, are used for cutting, grinding, and polishing.

Diamond crystallizes in the cubic system as octahedral crystals, some with curved faces and striations. The high refractive index of 2.42 and the high dispersion of light, or ‘fire’, account for the spectral displays seen in polished diamonds.

DaimlerChrysler Corp. v. Cuno,

547 U.S. ___ (2006) was a case decided by the Supreme Court of the United States involving the standing of taxpayers to challenge state tax laws in federal court. The Court unanimously ruled that state taxpayers did not have standing under Article III of the United States Constitution to challenge state tax or spending decisions simply by virtue of their status as taxpayers.[1] Chief Justice John Roberts delivered the majority opinion (his fifth on the Court), which was joined by all of the justices except for Ruth Bader Ginsburg, who concurred separately. Background of the case

Diamond

Diamond -


One of five pedagogical languages based on Markov algorithms, used in "Nonpareil, a Machine Level Machine Independent Language for the Study of Semantics", B. Higman, ULICS Intl Report No ICSI 170, U London (1968). (cf. Brilliant, Nonpareil, Pearl[3], Ruby[2]).


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diamond

token of affection, e.g., for engagement. [Gem Symbolism: Jobes, 440–441]
See : Love
Allusions—Cultural, Literary, Biblical, and Historical: A Thematic Dictionary. Copyright 2008 The Gale Group, Inc. All rights reserved.

diamond

April birthstone, most reflective of gems. [Gem Symbolism: Jobes, 440–441]
See : Brightness

diamond

April. [Am. Gem Symbolism: Kunz, 319–320]
See : Birthstones

diamond

1.
a. a colourless exceptionally hard mineral (but often tinted yellow, orange, blue, brown, or black by impurities), found in certain igneous rocks (esp the kimberlites of South Africa). It is used as a gemstone, as an abrasive, and on the working edges of cutting tools. Composition: carbon. Formula: C. Crystal structure: cubic
b. (as modifier): a diamond ring
2. Geometry
a. a figure having four sides of equal length forming two acute angles and two obtuse angles; rhombus
b. rhombic
3.
a. a red lozenge-shaped symbol on a playing card
b. a card with one or more of these symbols or (when plural) the suit of cards so marked
4. Baseball
a. the whole playing field
b. the square formed by the four bases
5. black diamond a figurative name for coal
6. rough diamond an unpolished diamond
www.adiamondisforever.com
www.amnh.org/exhibitions/diamonds
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

diamond

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.

For more information on diamond, visit Britannica.com. Britannica Concise Encyclopedia. Copyright © 1994-2008 Encyclopædia Britannica, Inc.

The Diamond Cartel

The discoveries of 1870–71 in South Africa led to a great number of prospectors staking out claims and securing the diamonds by open-pit or quarry mining. The damage caused by floods and mudslides, unavoidable when there were so many different claims, was an important factor in the series of amalgamations carried on by Cecil Rhodes Rhodes, Cecil John (sĕs`ĭl, rōdz), 1853–1902, British imperialist and business magnate.
..... Click the link for more information. and Barnett Barnato Barnato, Barnett (bärnä`tō), 1852–97, South African financier, b. London.
..... Click the link for more information. . Rhodes brought about the merging of their interests in the De Beers Consolidated Mines, Ltd., which established (1889) an effective monopoly over the diamond industry. Loss of diamonds by theft was reduced through the passage of the so-called I.D.B. (Illicit Diamond Buying) Act, which limited the trade to licensed buyers and imposed penalties for the possession of uncut stones without a license. Thefts were further curtailed by the institution of compounds in which the workers live while employed by the company and which they leave only after being thoroughly searched.

Most of the major diamond producers belong to, or have cooperated with, the De Beers–led marketing cartel, formed to maintain the price of diamonds at a high level. De Beers, under Harry Oppenheimer's leadership (1957–84), maintained its dominant position in the industry by using its numerous worldwide companies to buy up new sources of diamonds and to control distribution of industrial diamonds and production of synthetic ones. In the last decades of the 20th cent., however, De Beers' hold over the unpolished diamond market decreased, and in 2000 the company announced it would end to its policy of controlling diamond prices through hoarding and shift its focus to increasing sales.

Diadem or tiara of diamonds, gold, and silver with 25 five-point stars, graduated in size, set "en tremblant," containing 502 brilliants, 60 rose cuts; the central diamond of the largest star is 21.60 carats. By Estevao de Sousa, Lisbon, 1863-1866. Commissioned by Queen Maria Pia of Portugal (1847-1911). Both loaned by the National Palace of the Ajuda Museum, Lisbon.

JEWELRY GEMS

Riviere - a necklace "river" of diamonds. With 55 graduated diamonds, total weight 118 carats, set in silver on a gold chain. By Ambrosio Gottlieb Polett, Lisbon, second half of 18th century. Loaned by the National Palace of the Ajuda Museum, Lisbon.

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JEWELRY/GEMS

Part of the Aurora Collection of 260 naturally colored diamonds from worldwide sources representing the variety of fancy colors in diamonds. The stones range from 0.13 to 2.88 carats, and total 231.73 carats. Loaned by Aurora Gems, Inc., New York.

Diamond Color

Cut : Color : Clarity : Clarity Enhacement : Carat Weight : Certification : Caring : Diamond Shapes

Diamond Color
The color of a diamond depends on the quantity and nature of trace elements within the stone and how these elements originated. Most commercially available diamonds range in color from colorless to pale yellowish. There are other colors of diamonds known as "fancy diamonds" which can be pink, blue, green, yellow, brown and even black.

The GIA (Gemological Institute of America) provides a letter scale in which diamonds are graded based on their color. The following diagram illustrates the range of color grades:



NOTE: The colors on this chart are for demostration purposes only. Since all monitors display colors diferrently, what you see on this chart may not represent the exact color grade.

Diamonds that are graded in the D-F range are the rarest and consequently most valuable. In reality, diamonds in the G-K range have such a small amount of color that the untrained eye can not see it and as such offer a great value. In order to provide our customers with the finest possible selection of inventory, you will not find any diamonds rated below P in color on the web site. Fancy color diamonds are available in their own section and do not follow the letter grading conventions in the chart above.

Fluorescence
This characteristic of a diamond causes a slight blue glow when the stone is exposed to intense, direct ultraviolet light. This type of light can typically be found in nightclubs. A small amount of ultraviolet light comes directly from the sun.There are differing opinions on fluorescence and whether to avoid it or not. We believe it comes down to a matter of personal taste and does not affect the value of the diamond.

See The Diamond Before Paying

We believe that buying a diamond is a big decision and we want you to see your diamond in person before paying for anything. Learn more about how Yehuda.com works

Making Diamonds Look Better

Now you can afford the largest, most beautiful diamonds you've dreamed of thanks to the Yehuda diamond clarity enhancement process.

Browse Online, Buy In Person

Select any two clarity enhanced loose diamonds or pieces of finished diamond jewelry from our site and complete an online request. You will then receive an email with the contact information of the authorized Yehuda jeweler in your area. Give them a call and schedule an appointment. When we receive notice from the jeweler that an appointment has been scheduled, we will ship the exact diamonds you requested. Then on the day of your appointment, you can drop in to your local jewelry store and see the diamond face-to-face, touch it, inspect it with a jeweler's loupe and compare it to other more expensive non-enhanced diamonds.

If you decide to buy one of the diamonds we sent, you will pay the low internet price you see online, but get a knowledgable local jeweler's service to answer questions, mount the diamond, size the ring and complete your purchase.