Friday, June 6, 2014

The History of HTML

Unknown June 06, 2014 0 Comments

The History of HTML

A markup language combines text as well as coded instructions on how to format that text and the term "markup" originates from the traditional practice of 'marking up' the margins of a paper manuscript with printer's instructions. Nowadays, however, if you mention the term 'markup' to any knowledgeable web author, the first thing they are likely to think of is 'HTML'.

HTML —which is short for HyperText Markup Language— is the official language of the World Wide Web and was first conceived in 1990. HTML is a product of SGML (Standard Generalized Markup Language) which is a complex, technical specification describing markup languages, especially those used in electronic document exchange, document management, and document publishing. HTML was originally created to allow those who were not specialized in SGML to publish and exchange scientific and other technical documents. HTML especially facilitated this exchange by incorporating the ability to link documents electronically using hyperlinks. Thus the name Hypertext Markup Language.
However, it was quickly realized by those outside of the discipline of scientific documentation that HTML was relatively easy to learn, was self contained and lent itself to a number of other applications. With the evolution of the World Wide Web, HTML began to proliferate and quickly spilled over into the mainstream.

Soon, companies began creating browsers —the software required to view an HTML document, i.e., a web page— and as they gained popularity it gave rise to competition and other web browsers. It may surprise some that back in late 1995, Netscape —which now plays a distant second to the King Kong of browsers, Internet Explorer— was the dominant browser on the market. In fact, Netscape was the first browser to support Javascript, animated gifs and HTML frames.
Thus began the so-called 'browser wars' and, along with seeing who could implement more 'bells and whistles' than the other guy, browser makers also began inventing proprietary HTML elements that only worked with their browsers. Some examples of these are the <marquee>...</marquee> tags (scrolling text) which originally only worked with Internet Explorer and the <blink>...</blink> tags (blinking text) which still only works with Gecko-based browsers such as Firefox.
A side effect of all this competition was that HTML became fragmented and web authors soon found that their web pages looked fine in one browser but not in another. Hence it became increasingly difficult and time consuming to create a web page that would display uniformly across a number of different browsers. (This phenomenon remains to some extent to this very day.)

Meanwhile, an organization known as the World Wide Web Consortium (W3C for short) was working steadily along in the background to standardize HTML. Several recommendations were published by the W3C during the late 1990s which represented the official versions of HTML and provided an ongoing comprehensive reference for web authors. Thus the birth of HTML 2.0 in September 1995, HTML 3.2 in January 1997 and HTML 4.01 in December 1999.
By now, Internet Explorer (IE) had eclipsed Netscape Navigator as the browser to use while surfing the net due to its superior capabilities but also largely due to the fact that the IE came bundled with the Windows operating system. Essentially when people bought computers using the Windows OS, it had the 'internet installed on it'. This tended to suit people just fine since the typical newcomer to computers was someone who was tentatively striking forth to take on this intimidating new-fangled technology that was crammed to the rafters with indecipherable acronyms, software help files that made no sense and buggy programs. Hence, the more 'instant' solutions this new technology offered, the better it was.

As the World Wide Web approached adulthood hosting a wide variety of would-be and professional web page authors, it became increasingly apparent that cyberspace was filling up with a lot of badly written HTML.

This was due to some laziness and inexperience but was also the product of another instant solution involving web authoring tools, most particularly WYSIWYG editors, which tended to produce bloated and messy source code. As the browser wars continued —although by now it was pretty much of a massacre— the lead browser had developed capabilities akin to a junkyard dog which could gobble up any half-baked web page that it came across. This was all very fine and well but the resources (program source code, RAM on the user's computer, etcetera) required to run a browser that can consume just about anything was exhorbitant compared to what could be. And as the market dictated the shape of things to come, future browsers were bound follow the lead dog thus encouraging more junk code to fill up the web.

To remedy this situation, the W3C came up with a more regimental form of HTML with the intention to create a rigid standard to which web authors were encouraged to conform. This was supporting an effort to eventually 'clean up' or streamline the World Wide Web and ultimately replace presentational elements such as font with another documentational structure known as Cascading Style Sheets (CSS). In theory, once this transformation occurred, the web would place less demand on the next generation of web browsers and most specifically it would accomodate the low processing power of new portable devices such as PDAs. Hence the birth of the next generation of HTML called XHTML, the ' X ' representing that this version of HTML was based on XML (eXtensible Markup Language) instead of SGML.

the History of JavaScript

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JavaScript, not to be confused with Java, was created in 10 days in May 1995 by Brendan Eich, then working at Netscape and now of Mozilla. JavaScript was not always known as JavaScript: the original name was Mocha, a name chosen by Marc Andreessen, founder of Netscape. In September of 1995 the name was changed to LiveScript, then in December of the same year, upon receiving a trademark license from Sun, the name JavaScript was adopted. This was somewhat of a marketing move at the time, with Java being very popular around then.
In 1996 - 1997 JavaScript was taken to ECMA to carve out a standard specification, which other browser vendors could then implement based on the work done at Netscape. The work done over this period of time eventually led to the official release of ECMA-262 Ed.1: ECMAScript is the name of the official standard, with JavaScript being the most well known of the implementations. ActionScript 3 is another well-known implementation of ECMAScript, with extensions (see below).
The standards process continued in cycles, with releases of ECMAScript 2 in 1998 and ECMAScript 3 in 1999, which is the baseline for modern day JavaScript. The "JS2" or "original ES4" work led by Waldemar Horwat (then of Netscape, now at Google) started in 2000 and at first, Microsoft seemed to participate and even implemented some of the proposals in their JScript.net language.
Over time it was clear though that Microsoft had no intention of cooperating or implementing proper JS in IE, even though they had no competing proposal and they had a partial (and diverged at this point) implementation on the .NET server side. So by 2003 the JS2/original-ES4 work was mothballed.
The next major event was in 2005, with two major happenings in JavaScript’s history. First, Brendan Eich and Mozilla rejoined Ecma as a not-for-profit member and work started on E4X, ECMA-357, which came from ex-Microsoft employees at BEA (originally acquired as Crossgain). This led to working jointly with Macromedia, who were implementing E4X in ActionScript 3(ActionScript 3 was a fork of Waldemar's JS2/original-ES4 work).
So, along with Macromedia (later acquired by Adobe), work restarted on ECMAScript 4 with the goal of standardizing what was in AS3 and implementing it in SpiderMonkey. To this end, Adobe released the "AVM2", code named Tamarin, as an open source project. But Tamarin and AS3 were too different from web JavaScript to converge, as was realized by the parties in 2007 and 2008.
Alas, there was still turmoil between the various players; Doug Crockford — then at Yahoo! — joined forces with Microsoft in 2007 to oppose ECMAScript 4, which led to the ECMAScript 3.1 effort.
While all of this was happening the open source and developer communities set to work to revolutionize what could be done with JavaScript. This community effort was sparked in 2005 when Jesse James Garrett released a white paper in which he coined the term Ajax, and described a set of technologies, of which JavaScript was the backbone, used to create web applications where data can be loaded in the background, avoiding the need for full page reloads and resulting in more dynamic applications. This resulted in a renaissance period of JavaScript usage spearheaded by open source libraries and the communities that formed around them, with libraries such as Prototype, jQuery, Dojo and Mootools and others being released.
In July of 2008 the disparate parties on either side came together in Oslo. This led to the eventual agreement in early 2009 to rename ECMAScript 3.1 to ECMAScript 5 and drive the language forward using an agenda that is known as Harmony.
All of this then brings us to today, with JavaScript entering a completely new and exciting cycle of evolution, innovation and standardisation, with new developments such as the Nodejs platform, allowing us to use JavaScript on the server-side, and HTML5 APIs to control user media, open up web sockets for always-on communication, get data on geographical location and device features such as accelerometer, and more. It is an exciting time to learn JavaScript.

the history of In the Mughal

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After the greate period of the Gupta Empire and the reign of the Sultanate of Delhi, India saw the emergence of the largest ever empire with the rise of the Mughal rule in the country. The founder of this new state in India was Zahir-Ud-din Muhammad Babur, a descendant of Jenghis Khan and Timur the Lame. Babur had been thrown out of Central Asia earlier by the Uzbeks, but he managed to gain control of Afghan territories and then set his eyes on India by conquering which he could become more powerful and richer.
In 1518 and 1524 he attacked India and in 1525 he led a well organized army to Delhi. In the battle of Panipat, in 1526, he defeated Ibrahim Lodi, the last of the Delhi Sultans. The next year he defeated t
In the Mughal dynasty he founded, six emperors were famous – Babur (1526 –1530), Humayun (1530 – 1556), Akbar (1556 – 1605), Jehangir (1605 – 1627), Shah Jehan (1627 –1658), and Aurangazeb (1658 –1707). Of these, Akbar and Shah Jehan were two of the most important emperors in the history of India.

The history of Nokia

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The history of Nokia

Nokia was originally founded as a paper manufacturer by Fredrik Idestam in 1865. After having established a groundwood pulp mill in South-western Finland, Idestam in 1868 constructed a second mill in the nearby town of Nokia: having better resources for the generation of hydropower production. In 1971 Ideastam along with close friend Leo Mechelin transformed the firm into a share company, thereby founding the Nokia Company.
In the late 19th century Nokia added electricity generation to its business activities. After setting up the Finnish Cable Works in 1912, Nokia began to branch out into electronics in the 60s. Having developed its first electronic device in 1962 (a pulse analyser for use in nuclear power plants) Nokia began development on radio telephones in 1963 for the army and emergency services and by 1987 Nokia became the third largest TV manufacturer in Europe
n 1979 the company established the radio telephone company Mobira Oy as a joint venture with the Finnish TV maker Salora. Having established a firm business footing Nokia released the Nordic Mobile Telephone (NMT) service, the world’s first international cellular network. As the mobile phone industry expanded throughout the 1970s and early 1980s Nokia introduced their first car phone in 1982, the Mobira Senator.
In 1987 Nokia introduced the Mobira Cityman, the first handheld mobile phone for NMT networks. Although the phone was both heavy at 800g and expensive at €4560 it was well received – and is now considered a classic – in large part thanks to Mikhail Gorbachev after he was photographed using one. After having established themselves as major players in the mobile phone industry GSM was adopted as the European standard for digital mobile technology.
Nokia launched the 2100 series in 1994, the first to feature the Nokia Tune ringtone. After having established itself as one of the most frequently played and widely recognised pieces of music in the world the Nokia 2100 went on to sell 20 million phones worldwide (Nokia’s target had been 400,000). In addition to the ringtone Nokia in 1997 introduced the game of Snake: a game that is now replicated on over half a million phones.
By 1998 Nokia established itself as the world leader in mobile phones sales. Between 1996 and 2001 Nokia’s turnover increased by almost 500 percent from €6.5bn to €31bn. The exploding world-wide demand for mobile phones through the 90s caused a major logistics crisis for many mobile phone operators; however Nokia was, and still is today, renowned as being the best operator for handling such logistics.
Nokia in 1999 released the Nokia 7110, capable of rudimentary web-based functions, including email. Further developments in mobile technology meant that in 2001 Nokia launched its first phone with a built-in camera (Nokia 7650) and in 2002 their first video capture phone (Nokia 3650). Though it was in 2002 with Nokia’s first 3G phone (Nokia 6650) that mobile technology was to experience a radical technological shift. Here on phones were able to browse the web, download music, watch TV and provide listless other services.

Nokia was to sell its billionth phone in 2005 as mobile phone subscriptions surpassed 2bn in this same period. In 2007 Nokia was internationally recognised as the fifth most valued brand in the world.
In both 2009 and 2010 the Dow Jones Indexes ranked Nokia as the worlds most sustainable technology company as they set about developing their business methods and strategies in accordance with new environmental standards.
In October 2009 Nokia posted its first quarterly loss in more than a decade, largely thought to be a repercussion of HTC releasing the first phone to use Google’s Android operating system: the HTC Dream (as of today 60 percent of mobile phones are powered by Android). After a year of struggling to keep pace with iPhone and Android devices Nokia hired former Microsoft executive Stephen Elop as chief executive in September 2009.

In October of 2010 Elop outlined plans to make 1800 job cuts and to streamline Nokia’s Smartphone operations. After admitting its inferiority to Microsoft’s operating system Nokia moved away from Symbian and established a partnership with Microsoft.
Having spent 2010 onwards making thousands of job cuts and enduring the failed successes of its Lumia 800 Nokia were superseded by Samsung as the largest producer of mobile phones.
Nokia has more recently announced the new Lumia 920 as the flagship for Microsoft’s new operating system and have signed a deal to sell and lease back what were its headquarters for the past 16 years.

the history of Windows

Unknown June 06, 2014 0 Comments

It’s the 1970s. At work, we rely on typewriters. If we need to copy a document, we likely use a mimeograph or carbon paper. Few have heard of microcomputers, but two young computer enthusiasts, Bill Gates and Paul Allen, see that personal computing is a path to the future.

In 1975, Gates and Allen form a partnership called Microsoft. Like most start-ups, Microsoft begins small, but has a huge vision—a computer on every desktop and in every home. During the next years, Microsoft begins to change the ways we wor

The dawn of MS‑DOS

In June 1980, Gates and Allen hire Gates’ former Harvard classmate Steve Ballmer to help run the company. The next month, IBM approaches Microsoft about a project code-named "Chess." In response, Microsoft focuses on a new operating system—the software that manages, or runs, the computer hardware and also serves to bridge the gap between the computer hardware and programs, such as a word processor. It’s the foundation on which computer programs can run. They name their new operating system "MS‑DOS."

When the IBM PC running MS‑DOS ships in 1981, it introduces a whole new language to the general public. Typing “C:” and various cryptic commands gradually becomes part of daily work. People discover the backslash (\) key.

MS‑DOS is effective, but also proves difficult to understand for many people. There has to be a better way to build an operating system. MS‑DOS stands for Microsoft Disk Operating System

Tuesday, May 6, 2014

the history of Diamond

Unknown May 06, 2014 0 Comments

history of Diamond

In mineralogy, diamond (from the ancient Greek αδάμας – adámas "unbreakable") is a metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at standard conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the strong covalent bonding between its atoms. In particular, diamond has the highest hardness and thermal conductivity of any bulk material. Those properties determine the major industrial application of diamond in cutting and polishing tools and the scientific applications in diamond knives and diamond anvil cells.

Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron andnitrogen. Small amounts of defects or impurities (about one per million of lattice atoms) color diamond blue (boron), yellow (nitrogen), brown (lattice defects), green (radiation exposure), purple, pink, orange or red. Diamond also has relatively high optical dispersion (ability to disperse light of different colors).

Most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers (87 to 118 mi) in the Earth's mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25% to 75% of the age of the Earth). Diamonds are brought close to the Earth′s surface through deep volcanic eruptions by a magma, which cools into igneous rocks known as kimberlites and lamproites. Diamonds can also be produced synthetically in a high-pressure high-temperature process which approximately simulates the conditions in the Earth's mantle. An alternative, and completely different growth technique is chemical vapor deposition (CVD). Several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties. Special gemological techniques have been developed to distinguish natural and synthetic diamonds and diamond simulants.

History

Natural history

The formation of natural diamond requires very specific conditions—exposure of carbon-bearing materials to high pressure, ranging approximately between 45 and 60 kilobars (4.5 and 6 GPa), but at a comparatively low temperature range between approximately 900 and 1,300 °C (1,650 and 2,370 °F). These conditions are met in two places on Earth; in the lithospheric mantle below relatively stable continental plates, and at the site of a meteorite strike.

Formation in cratons

A triangular facet of a crystal having triangular etch pits with the largest having a base length of about 0.2 millimetres (0.0079 in)

One face of an uncut octahedral diamond, showing trigons (of positive and negative relief) formed by natural chemical etching

The conditions for diamond formation to happen in the lithospheric mantle occur at considerable depth corresponding to the requirements of temperature and pressure. These depths are estimated between 140 and 190 kilometers (87 and 118 mi) though occasionally diamonds have crystallized at depths about 300 kilometers (190 mi).^[13] The rate at which temperature changes with increasing depth into the Earth varies greatly in different parts of the Earth. In particular, under oceanic plates the temperature rises more quickly with depth, beyond the range required for diamond formation at the depth required. The correct combination of temperature and pressure is only found in the thick, ancient, and stable parts of continental plates where regions of lithosphere known as cratons exist. Long residence in the cratonic lithosphere allows diamond crystals to grow larger.

Through studies of carbon isotope ratios (similar to the methodology used in carbon dating, except with the stable isotopes C-12 and C-13), it has been shown that the carbon found in diamonds comes from both inorganic and organic sources. Some diamonds, known as harzburgitic, are formed from inorganic carbon originally found deep in the Earth's mantle. In contrast, eclogitic diamonds contain organic carbon from organic detritus that has been pushed down from the surface of the Earth's crust through subduction (see plate tectonics) before transforming into diamond. These two different source of carbon have measurably different ¹³C:¹²C ratios. Diamonds that have come to the Earth's surface are generally quite old, ranging from under 1 billion to 3.3 billion years old. This is 22% to 73% of the age of the Earth.

Diamonds occur most often as euhedral or rounded octahedra and twinned octahedra known as macles. As diamond's crystal structure has a cubic arrangement of the atoms, they have many facets that belong to a cube, octahedron, rhombicosidodecahedron, tetrakis hexahedron or disdyakis dodecahedron. The crystals can have rounded off and unexpressive edges and can be elongated. Sometimes they are found grown together or form double "twinned" crystals at the surfaces of the octahedron. These different shapes and habits of some diamonds result from differing external circumstances. Diamonds (especially those with rounded crystal faces) are commonly found coated in nyf, an opaque gum-like skin.

Space diamonds

Transport from mantle

Diamond-bearing rock is carried from the mantle to the Earth's surface by deep-origin volcanic eruptions. The magma for such a volcano must originate at a depth where diamonds can be formed^[13]—150 km (93 mi) or more (three times or more the depth of source magma for most volcanoes). This is a relatively rare occurrence. These typically small surface volcanic craters extend downward in formations known as volcanic pipes.^[13] The pipes contain material that was transported toward the surface by volcanic action, but was not ejected before the volcanic activity ceased. During eruption these pipes are open to the surface, resulting in open circulation; many xenoliths of surface rock and even wood and fossils are found in volcanic pipes. Diamond-bearing volcanic pipes are closely related to the oldest, coolest regions of continental crust (cratons). This is because cratons are very thick, and their lithospheric mantle extends to great enough depth that diamonds are stable. Not all pipes contain diamonds, and even fewer contain enough diamonds to make mining economically viable.^[13] Diamonds are very rare^[22] because most of the crust is too thin to permit diamond crystallization, whereas most of the mantle has relatively little carbon.

The magma in volcanic pipes is usually one of two characteristic types, which cool into igneous rock known as either kimberlite or lamproite.^[13] The magma itself does not contain diamond; instead, it acts as an elevator that carries deep-formed rocks (xenoliths), minerals (xenocrysts), and fluids upward. These rocks are characteristically rich in magnesium-bearing olivine, pyroxene, and amphiboleminerals^[13] which are often altered to serpentine by heat and fluids during and after eruption. Certain indicator minerals typically occur within diamantiferous kimberlites and are used as mineralogical tracers by prospectors, who follow the indicator trail back to the volcanic pipe which may contain diamonds. These minerals are rich in chromium (Cr) or titanium (Ti), elements which impart bright colors to the minerals. The most common indicator minerals are chromium garnets (usually bright red chromium-pyrope, and occasionally green ugrandite-series garnets), eclogitic garnets, orange titanium-pyrope, red high-chromium spinels, dark chromite, bright green chromium-diopside, glassy green olivine, black picroilmenite, and magnetite. Kimberlite deposits are known as blue ground for the deeper serpentinized part of the deposits, or as yellow ground for the near surface smectite clay and carbonate weathered and oxidized portion.

Once diamonds have been transported to the surface by magma in a volcanic pipe, they may erode out and be distributed over a large area. A volcanic pipe containing diamonds is known as a primary source of diamonds. Secondary sources of diamonds include all areas where a significant number of diamonds have been eroded out of their kimberlite or lamproite matrix, and accumulated because of water or wind action. These include alluvial deposits and deposits along existing and ancient shorelines, where loose diamonds tend to accumulate because of their size and density. Diamonds have also rarely been found in deposits left behind by glaciers (notably in Wisconsin and Indiana); in contrast to alluvial deposits, glacial deposits are minor and are therefore not viable commercial sources of diamond.

Material properties

Main articles: Material properties of diamond and Crystallographic defects in diamond

Theoretically predicted phase diagram of carbon

Four panels. First, seven clear faceted gems, six small and a large one. Second, black material with uneven surface. Third, three parallel atomic sheets, each resembling a chicken wire hedge. Fourth, a boxed atomic structure containing tetrahedrally arranged balls connected by 0.15 nm bonds.

Diamond and graphite are twoallotropes of carbon: pure forms of the same element that differ in structure.

A diamond is a transparent crystal of tetrahedrally bonded carbon atoms in a covalent network lattice (sp³) that crystallizes into the diamond lattice which is a variation of the face centered cubic structure. Diamonds have been adapted for many uses because of the material's exceptional physical characteristics. Most notable are its extreme hardness and thermal conductivity (900–2,320 W·m⁻¹·K⁻¹),^[23] as well as wide bandgap and high optical dispersion.^[24]Above 1,700 °C (1,973 K / 3,583 °F) in vacuum or oxygen-free atmosphere, diamond converts to graphite; in air, transformation starts at ~700 °C.^[25] Diamond's ignition point is 720 – 800 °C in oxygen and 850 – 1,000 °C in air.^[26] Naturally occurring diamonds have a density ranging from 3.15–3.53 g/cm³, with pure diamond close to3.52 g/cm³.^[1] The chemical bonds that hold the carbon atoms in diamonds together are weaker than those in graphite. In diamonds, the bonds form an inflexible three-dimensional lattice, whereas in graphite, the atoms are tightly bonded into sheets, which can slide easily over one another, making the overall structure weaker.

Hardness

Diamond is the hardest known natural material on the Mohs scale of mineral hardness, where hardness is defined as resistance to scratching and is graded between 1 (softest) and 10 (hardest). Diamond has a hardness of 10 (hardest) on this scale.^[28] Diamond's hardness has been known since antiquity, and is the source of its name.

Diamond hardness depends on its purity, crystalline perfection and orientation: hardness is higher for flawless, pure crystals oriented to the <111> direction (along the longest diagonal of the cubic diamond lattice).^[29] Therefore, whereas it might be possible to scratch some diamonds with other materials, such as boron nitride, the hardest diamonds can only be scratched by other diamonds and nanocrystalline diamond aggregates.

The hardness of diamond contributes to its suitability as a gemstone. Because it can only be scratched by other diamonds, it maintains its polish extremely well. Unlike many other gems, it is well-suited to daily wear because of its resistance to scratching—perhaps contributing to its popularity as the preferred gem inengagement or wedding rings, which are often worn every day.

The extreme hardness of diamond in certain orientations makes it useful in materials science, as in this pyramidal diamond embedded in the working surface of a Vickers hardness tester.

The hardest natural diamonds mostly originate from the Copeton and Bingara fields located in the New England area in New South Wales, Australia. These diamonds are generally small, perfect to semiperfect octahedra, and are used to polish other diamonds. Their hardness is associated with the crystal growth form, which is single-stage crystal growth. Most other diamonds show more evidence of multiple growth stages, which produce inclusions, flaws, and defect planes in the crystal lattice, all of which affect their hardness. It is possible to treat regular diamonds under a combination of high pressure and high temperature to produce diamonds that are harder than the diamonds used in hardness gauges.^[20]

Somewhat related to hardness is another mechanical property toughness, which is a material's ability to resist breakage from forceful impact. The toughness of natural diamond has been measured as 7.5–10 MPa·m^1/2.^[30]^[31] This value is good compared to other gemstones, but poor compared to most engineering materials. As with any material, the macroscopic geometry of a diamond contributes to its resistance to breakage. Diamond has a cleavage plane and is therefore more fragile in some orientations than others. Diamond cutters use this attribute to cleave some stones, prior to faceting.^[32] "Impact toughness" is one of the main indexes to measure the quality of synthetic industrial diamonds.

Electrical conductivity

Other specialized applications also exist or are being developed, including use as semiconductors: some blue diamonds are natural semiconductors, in contrast to most diamonds, which are excellent electrical insulators.^[33] The conductivity and blue color originate from boron impurity. Boron substitutes for carbon atoms in the diamond lattice, donating a hole into the valence band.^[33]

Substantial conductivity is commonly observed in nominally undoped diamond grown by chemical vapor deposition. This conductivity is associated with hydrogen-related species adsorbed at the surface, and it can be removed by annealing or other surface treatments.

Surface property

Diamonds are naturally lipophilic and hydrophobic, which means the diamonds' surface cannot be wet by water but can be easily wet and stuck by oil. This property can be utilized to extract diamonds using oil when making synthetic diamonds.^[26] However, when diamond surfaces are chemically modified with certain ions, they are expected to become so hydrophilic that they can stabilize multiple layers of water ice at human body temperature.

Chemical stability

Diamonds are not very reactive. Under room temperature diamonds do not react with any chemical reagents including strong acids and bases. A diamond's surface can only be oxidized a little by just a few oxidants^[which?] at high temperature (below 1,000 °C). Therefore, acids and bases can be used to refine synthetic diamonds.

Color

Main article: Diamond color

A museum display of jewelry items. Three brooches each consist of a large brown central gem surrounded by many clear small stones. A necklace has a large brown gem at its bottom and its string is all covered with small clear gems. A cluster-shaped decoration contains many brown gems.

Brown diamonds at the National Museum of Natural History in Washington, D.C.

Diamond has a wide bandgap of 5.5 eV corresponding to the deep ultraviolet wavelength of 225 nanometers. This means pure diamond should transmit visible light and appear as a clear colorless crystal. Colors in diamond originate from lattice defects and impurities. The diamond crystal lattice is exceptionally strong and only atoms of nitrogen, boron and hydrogen can be introduced into diamond during the growth at significant concentrations (up to atomic percents). Transition metals Ni and Co, which are commonly used for growth of synthetic diamond by high-pressure high-temperature techniques, have been detected in diamond as individual atoms; the maximum concentration is 0.01% for Ni^[37] and even much less for Co. Virtually any element can be introduced to diamond by ion implantation.^[38]

Nitrogen is by far the most common impurity found in gem diamonds and is responsible for the yellow and brown color in diamonds. Boron is responsible for the blue color.^[24] Color in diamond has two additional sources: irradiation (usually by alpha particles), that causes the color in green diamonds; and plastic deformation of the diamond crystal lattice. Plastic deformation is the cause of color in some brown^[39] and perhaps pink and red diamonds.^[40] In order of rarity, yellow diamond is followed by brown, colorless, then by blue, green, black, pink, orange, purple, and red.^[32] "Black", or Carbonado, diamonds are not truly black, but rather contain numerous dark inclusions that give the gems their dark appearance. Colored diamonds contain impurities or structural defects that cause the coloration, while pure or nearly pure diamonds are transparent and colorless. Most diamond impurities replace a carbon atom in the crystal lattice, known as a carbon flaw. The most common impurity, nitrogen, causes a slight to intense yellow coloration depending upon the type and concentration of nitrogen present.^[32] The Gemological Institute of America (GIA) classifies low saturation yellow and brown diamonds as diamonds in the normal color range, and applies a grading scale from "D" (colorless) to "Z" (light yellow). Diamonds of a different color, such as blue, are called fancy colored diamonds, and fall under a different grading scale.

In 2008, the Wittelsbach Diamond, a 35.56-carat (7.112 g) blue diamond once belonging to the King of Spain, fetched over US$24 million at a Christie's auction.^[41]In May 2009, a 7.03-carat (1.406 g) blue diamond fetched the highest price per carat ever paid for a diamond when it was sold at auction for 10.5 million Swiss francs (6.97 million euro or US$9.5 million at the time).^[42] That record was however beaten the same year: a 5-carat (1.0 g) vivid pink diamond was sold for $10.8 million in Hong Kong on December 1, 2009.

Identification

Diamonds can be identified by their high thermal conductivity. Their high refractive index is also indicative, but other materials have similar refractivity. Diamonds cut glass, but this does not positively identify a diamond because other materials, such as quartz, also lie above glass on the Mohs scale and can also cut it. Diamonds can scratch other diamonds, but this can result in damage to one or both stones. Hardness tests are infrequently used in practical gemology because of their potentially destructive nature.^[28] The extreme hardness and high value of diamond means that gems are typically polished slowly using painstaking traditional techniques and greater attention to detail than is the case with most other gemstones;^[10] these tend to result in extremely flat, highly polished facets with exceptionally sharp facet edges. Diamonds also possess an extremely high refractive index and fairly high dispersion. Taken together, these factors affect the overall appearance of a polished diamond and most diamantaires still rely upon skilled use of a loupe (magnifying glass) to identify diamonds 'by eye'.^[44]

Industry

A clear faceted gem supported in four clamps attached to a wedding ring

A round brilliant cut diamond set in a ring

Gem-grade diamonds

Main article: Diamond (gemstone)

A large trade in gem-grade diamonds exists. Unlike other commodities, such as most precious metals, there is a substantial mark-up in the retail sale of gem diamonds.^[45] There is a well-established market for resale of polished diamonds (e.g. pawnbroking, auctions, second-hand jewelry stores, diamantaires, bourses, etc.). One hallmark of the trade in gem-quality diamonds is its remarkable concentration: wholesale trade and diamond cutting is limited to just a few locations; in 2003, 92% of the world's diamonds were cut and polished in Surat, India.^[46] Other important centers of diamond cutting and trading are theAntwerp diamond district in Belgium, where the International Gemological Institute is based, London, the Diamond District in New York City, Tel Aviv, and Amsterdam. A single company – De Beers – controls a significant proportion of the trade in diamonds.^[47] They are based in Johannesburg, South Africa and London, England. One contributory factor is the geological nature of diamond deposits: several large primary kimberlite-pipe mines each account for significant portions of market share (such as the Jwaneng mine in Botswana, which is a single large pit operated by De Beers that can produce between 12,500,000 carats (2,500 kg) to 15,000,000 carats (3,000 kg) of diamonds per year,^[48]) whereas secondary alluvial diamond deposits tend to be fragmented amongst many different operators because they can be dispersed over many hundreds of square kilometers (e.g., alluvial deposits in Brazil).

The production and distribution of diamonds is largely consolidated in the hands of a few key players, and concentrated in traditional diamond trading centers, the most important being Antwerp, where 80% of all rough diamonds, 50% of all cut diamonds and more than 50% of all rough, cut and industrial diamonds combined are handled.^[49] This makes Antwerp a de facto "world diamond capital".^[50] Another important diamond center is New York City, where almost 80% of the world's diamonds are sold, including auction sales.^[49] The DeBeers company, as the world's largest diamond miner holds a dominant position in the industry, and has done so since soon after its founding in 1888 by the British imperialist Cecil Rhodes. De Beers owns or controls a significant portion of the world's rough diamond production facilities (mines) and distribution channels for gem-quality diamonds. The Diamond Trading Company (DTC) is a subsidiary of De Beers and markets rough diamonds from De Beers-operated mines. De Beers and its subsidiaries own mines that produce some 40% of annual world diamond production. For most of the 20th century over 80% of the world's rough diamonds passed through De Beers,^[51] but by 2001–2009 the figure had decreased to around 45%,^[52] and by 2013 the company's market share had further decreased to around 38% in value terms and even less by volume.^[53] De Beers sold off the vast majority of its diamond stockpile in the late 1990s – early 2000s^[54] and the remainder largely represents working stock (diamonds that are being sorted before sale).^[55] This was well documented in the press^[56] but remains little known to the general public.

As a part of reducing its influence, De Beers withdrew from purchasing diamonds on the open market in 1999 and ceased, at the end of 2008, purchasing Russian diamonds mined by the largest Russian diamond company Alrosa.^[57] As of January 2011, De Beers states that it only sells diamonds from the following four countries: Botswana, Namibia, South Africa and Canada.^[58] Alrosa had to suspend their sales in October 2008 due to the global energy crisis,^[59] but the company reported that it had resumed selling rough diamonds on the open market by October 2009.^[60] Apart from Alrosa, other important diamond mining companies includeBHP Billiton, which is the world's largest mining company;^[61] Rio Tinto Group, the owner of Argyle (100%), Diavik (60%), and Murowa (78%) diamond mines;^[62] andPetra Diamonds, the owner of several major diamond mines in Africa.

Diamond polisher in Amsterdam

Further down the supply chain, members of The World Federation of Diamond Bourses (WFDB) act as a medium for wholesale diamond exchange, trading both polished and rough diamonds. The WFDB consists of independent diamond bourses in major cutting centers such as Tel Aviv, Antwerp, Johannesburg and other cities across the USA, Europe and Asia.^[32] In 2000, the WFDB and The International Diamond Manufacturers Association established the World Diamond Council to prevent the trading of diamonds used to fund war and inhumane acts. WFDB's additional activities include sponsoring the World Diamond Congress every two years, as well as the establishment of the International Diamond Council(IDC) to oversee diamond grading.

Once purchased by Sightholders (which is a trademark term referring to the companies that have a three-year supply contract with DTC), diamonds are cut and polished in preparation for sale as gemstones ('industrial' stones are regarded as a by-product of the gemstone market; they are used for abrasives).^[63] The cutting and polishing of rough diamonds is a specialized skill that is concentrated in a limited number of locations worldwide.^[63] Traditional diamond cutting centers are Antwerp, Amsterdam, Johannesburg, New York City, and Tel Aviv. Recently, diamond cutting centers have been established in China, India, Thailand, Namibia and Botswana.^[63] Cutting centers with lower cost of labor, notably Surat inGujarat, India, handle a larger number of smaller carat diamonds, while smaller quantities of larger or more valuable diamonds are more likely to be handled in Europe or North America. The recent expansion of this industry in India, employing low cost labor, has allowed smaller diamonds to be prepared as gems in greater quantities than was previously economically feasible.^[49]

Diamonds which have been prepared as gemstones are sold on diamond exchanges called bourses. There are 28 registered diamond bourses in the world.^[64]Bourses are the final tightly controlled step in the diamond supply chain; wholesalers and even retailers are able to buy relatively small lots of diamonds at the bourses, after which they are prepared for final sale to the consumer. Diamonds can be sold already set in jewelry, or sold unset ("loose"). According to the Rio Tinto Group, in 2002 the diamonds produced and released to the market were valued at US$9 billion as rough diamonds, US$14 billion after being cut and polished, US$28 billion in wholesale diamond jewelry, and US$57 billion in retail sales.

Cutting

Main articles: Diamond cutting and Diamond cut

A large rectangular pink multifaceted gemstone, set in a decorative surround. The decoration includes a row of small clear faceted gemstones around the main gem's perimeter, and clusters of gems forming a crest on one side. The crest comprises a three-pointed crown faced by two unidentifiable animals.

The Darya-I-Nur Diamond—an example of unusual diamond cut and jewelry arrangement

Mined rough diamonds are converted into gems through a multi-step process called "cutting". Diamonds are extremely hard, but also brittle and can be split up by a single blow. Therefore, diamond cutting is traditionally considered as a delicate procedure requiring skills, scientific knowledge, tools and experience. Its final goal is to produce a faceted jewel where the specific angles between the facets would optimize the diamond luster, that is dispersion of white light, whereas the number and area of facets would determine the weight of the final product. The weight reduction upon cutting is significant and can be of the order of 50%.^[66] Several possible shapes are considered, but the final decision is often determined not only by scientific, but also practical considerations. For example the diamond might be intended for display or for wear, in a ring or a necklace, singled or surrounded by other gems of certain color and shape.

The most time-consuming part of the cutting is the preliminary analysis of the rough stone. It needs to address a large number of issues, bears much responsibility, and therefore can last years in case of unique diamonds. The following issues are considered:

The hardness of diamond and its ability to cleave strongly depend on the crystal orientation. Therefore, the crystallographic structure of the diamond to be cut is analyzed using X-ray diffraction to choose the optimal cutting directions.
Most diamonds contain visible non-diamond inclusions and crystal flaws. The cutter has to decide which flaws are to be removed by the cutting and which could be kept.
The diamond can be split by a single, well calculated blow of a hammer to a pointed tool, which is quick, but risky. Alternatively, it can be cut with a diamond saw, which is a more reliable but tedious procedure.^[67]^[68]

After initial cutting, the diamond is shaped in numerous stages of polishing. Unlike cutting, which is a responsible but quick operation, polishing removes material by gradual erosion and is extremely time consuming. The associated technique is well developed; it is considered as a routine and can be performed by technicians.^[69]After polishing, the diamond is reexamined for possible flaws, either remaining or induced by the process. Those flaws are concealed through various diamond enhancement techniques, such as repolishing, crack filling, or clever arrangement of the stone in the jewelry. Remaining non-diamond inclusions are removed through laser drilling and filling of the voids produced.

Marketing

Marketing has significantly affected the image of diamond as a valuable commodity.

N. W. Ayer & Son, the advertising firm retained by De Beers in the mid-20th century, succeeded in reviving the American diamond market. And the firm created new markets in countries where no diamond tradition had existed before. N. W. Ayer's marketing included product placement, advertising focused on the diamond product itself rather than the De Beers brand, and associations with celebrities and royalty. Without advertising the De Beers brand, De Beers was also advertising its competitors' diamond products as well^[70] (De Beers' market share dipped temporarily to 2nd place in the global market below Alrosa in the aftermath of the global economic crisis of 2008, down to less than 29% in terms of carats mined, rather than sold^[71]). The campaign lasted for decades but was effectively discontinued by early 2011. De Beers still advertises diamonds, but the advertising now mostly promotes its own brands, or licensed product lines, rather than completely "generic" diamond products.^[71] The campaign was perhaps best captured by the slogan "a diamond is forever".^[7] This slogan is now being used by De Beers Diamond Jewelers,^[72] a jewelry firm which is a 50%/50% joint venture between the De Beers mining company and LVMH, the luxury goods conglomerate.

Brown-colored diamonds constituted a significant part of the diamond production, and were predominantly used for industrial purposes. They were seen as worthless for jewelry (not even being assessed on the diamond color scale). After the development of Argyle diamond mine in Australia in 1986, and marketing, brown diamonds have become acceptable gems.^[73]^[74] The change was mostly due to the numbers: the Argyle mine, with its 35,000,000 carats (7,000 kg) of diamonds per year, makes about one-third of global production of natural diamonds;^[75] 80% of Argyle diamonds are brown.

Industrial-grade diamonds

A diamond scalpel consisting of a yellow diamond blade attached to a pen-shaped holder

A scalpel with synthetic diamond blade

A polished metal blade embedded with small diamonds

Close-up photograph of an angle grinder blade with tiny diamonds shown embedded in the metal

A diamond knife blade used for cutting ultrathin sections (typically 70 to 350 nm for transmission electron microscopy.

Industrial diamonds are valued mostly for their hardness and thermal conductivity, making many of the gemological characteristics of diamonds, such as the 4 Cs, irrelevant for most applications. 80% of mined diamonds (equal to about 135,000,000 carats (27,000 kg) annually), are unsuitable for use as gemstones, and used industrially.^[77] In addition to mined diamonds, synthetic diamonds found industrial applications almost immediately after their invention in the 1950s; another 570,000,000 carats (114,000 kg) of synthetic diamond is produced annually for industrial use. Approximately 90% of diamond grinding grit is currently of synthetic origin.^[78]

The boundary between gem-quality diamonds and industrial diamonds is poorly defined and partly depends on market conditions (for example, if demand for polished diamonds is high, some lower-grade stones will be polished into low-quality or small gemstones rather than being sold for industrial use). Within the category of industrial diamonds, there is a sub-category comprising the lowest-quality, mostly opaque stones, which are known as bort.

Industrial use of diamonds has historically been associated with their hardness, which makes diamond the ideal material for cutting and grinding tools. As the hardest known naturally occurring material, diamond can be used to polish, cut, or wear away any material, including other diamonds. Common industrial applications of this property include diamond-tipped drill bitsand saws, and the use of diamond powder as an abrasive. Less expensive industrial-grade diamonds, known as bort, with more flaws and poorer color than gems, are used for such purposes.^[80] Diamond is not suitable for machining ferrous alloysat high speeds, as carbon is soluble in iron at the high temperatures created by high-speed machining, leading to greatly increased wear on diamond tools compared to alternatives.

Specialized applications include use in laboratories as containment for high pressure experiments (see diamond anvil cell), high-performance bearings, and limited use in specialized windows.^[79] With the continuing advances being made in the production of synthetic diamonds, future applications are becoming feasible. The high thermal conductivity of diamond makes it suitable as a heat sink for integrated circuits in electronics.

Mining

Approximately 130,000,000 carats (26,000 kg) of diamonds are mined annually, with a total value of nearly US$9 billion, and about 100,000 kg (220,000 lb) are synthesized annually.^[83]

Roughly 49% of diamonds originate from Central and Southern Africa, although significant sources of the mineral have been discovered in Canada, India, Russia, Brazil, and Australia.^[78] They are mined from kimberlite and lamproite volcanic pipes, which can bring diamond crystals, originating from deep within the Earth where high pressures and temperatures enable them to form, to the surface. The mining and distribution of natural diamonds are subjects of frequent controversy such as concerns over the sale of blood diamonds or conflict diamonds by African paramilitary groups.^[84] The diamond supply chain is controlled by a limited number of powerful businesses, and is also highly concentrated in a small number of locations around the world.

Only a very small fraction of the diamond ore consists of actual diamonds. The ore is crushed, during which care is required not to destroy larger diamonds, and then sorted by density. Today, diamonds are located in the diamond-rich density fraction with the help of X-ray fluorescence, after which the final sorting steps are done by hand. Before the use of X-rays became commonplace,^[66] the separation was done with grease belts; diamonds have a stronger tendency to stick to grease than the other minerals in the ore.

Siberia's Udachnaya diamond mine

Historically, diamonds were found only in alluvial deposits in Guntur and Krishna district of the Krishna River delta in Southern India.^[85] India led the world in diamond production from the time of their discovery in approximately the 9th century BC^[4]^[86]to the mid-18th century AD, but the commercial potential of these sources had been exhausted by the late 18th century and at that time India was eclipsed by Brazil where the first non-Indian diamonds were found in 1725.^[4] Currently, one of the most prominent Indian mines is located at Panna.

Diamond extraction from primary deposits (kimberlites and lamproites) started in the 1870s after the discovery of theDiamond Fields in South Africa.^[88] Production has increased over time and now an accumulated total of 4,500,000,000 carats (900,000 kg) have been mined since that date.^[89] Twenty percent of that amount has been mined in the last five years, and during the last 10 years, nine new mines have started production; four more are waiting to be opened soon. Most of these mines are located in Canada, Zimbabwe, Angola, and one in Russia.

In the U.S., diamonds have been found in Arkansas, Colorado, Wyoming, and Montana.^[90]^[91] In 2004, the discovery of a microscopic diamond in the U.S. led to the January 2008 bulk-sampling of kimberlite pipes in a remote part of Montana.

Today, most commercially viable diamond deposits are in Russia (mostly in Sakha Republic, for example Mir pipe and Udachnaya pipe), Botswana, Australia (Northern and Western Australia) and the Democratic Republic of Congo.^[92] In 2005, Russia produced almost one-fifth of the global diamond output, reports theBritish Geological Survey. Australia boasts the richest diamantiferous pipe, with production from the Argyle diamond mine reaching peak levels of 42 metric tons per year in the 1990s.^[90]^[93] There are also commercial deposits being actively mined in the Northwest Territories of Canada and Brazil.^[78] Diamond prospectors continue to search the globe for diamond-bearing kimberlite and lamproite pipes.

Political issues

Unsustainable diamond mining in Sierra Leone

Main articles: Kimberley Process, Blood diamond and Child labour in the diamond industry

In some of the more politically unstable central African and west African countries, revolutionary groups have taken control ofdiamond mines, using proceeds from diamond sales to finance their operations. Diamonds sold through this process are known as conflict diamonds or blood diamonds.^[84] Major diamond trading corporations continue to fund and fuel these conflicts by doing business with armed groups. In response to public concerns that their diamond purchases were contributing to war and human rights abuses in central and western Africa, the United Nations, the diamond industry and diamond-trading nations introduced the Kimberley Process in 2002.^[94] The Kimberley Process aims to ensure that conflict diamonds do not become intermixed with the diamonds not controlled by such rebel groups. This is done by requiring diamond-producing countries to provide proof that the money they make from selling the diamonds is not used to fund criminal or revolutionary activities. Although the Kimberley Process has been moderately successful in limiting the number of conflict diamonds entering the market, some still find their way in. Conflict diamonds constitute 2–3% of all diamonds traded.^[95] Two major flaws still hinder the effectiveness of the Kimberley Process: (1) the relative ease of smuggling diamonds across African borders, and (2) the violent nature of diamond mining in nations that are not in a technical state of war and whose diamonds are therefore considered "clean".

The Canadian Government has set up a body known as Canadian Diamond Code of Conduct^[96] to help authenticate Canadian diamonds. This is a stringent tracking system of diamonds and helps protect the "conflict free" label of Canadian diamonds.

Synthetics, simulants, and enhancements

Synthetics

Main article: Synthetic diamond

Six crystals of cubo-octahedral shapes, each about 2 millimeters in diameter. Two are pale blue, one is pale yellow, one is green-blue, one is dark blue and one green-yellow.

Synthetic diamonds of various colors grown by the high-pressure high-temperature technique

Synthetic diamonds are diamonds manufactured in a laboratory, as opposed to diamonds mined from the Earth. The gemological and industrial uses of diamond have created a large demand for rough stones. This demand has been satisfied in large part by synthetic diamonds, which have been manufactured by various processes for more than half a century. However, in recent years it has become possible to produce gem-quality synthetic diamonds of significant size.^[13] It is possible to make colorless synthetic gemstones that, on a molecular level, are identical to natural stones and so visually similar that only a gemologist with special equipment can tell the difference.^[98]

The majority of commercially available synthetic diamonds are yellow and are produced by so-called High Pressure High Temperature (HPHT) processes.^[99] The yellow color is caused by nitrogen impurities. Other colors may also be reproduced such as blue, green or pink, which are a result of the addition of boron or from irradiation after synthesis.^[100]

A round, clear gemstone with many facets, the main face being hexagonal, surrounded by many smaller facets.

Colorless gem cut from diamond grown by chemical vapor deposition

Another popular method of growing synthetic diamond is chemical vapor deposition (CVD). The growth occurs under low pressure (below atmospheric pressure). It involves feeding a mixture of gases (typically 1 to 99 methane to hydrogen) into a chamber and splitting them to chemically active radicals in a plasma ignited by microwaves, hot filament, arc discharge,welding torch or laser.^[101] This method is mostly used for coatings, but can also produce single crystals several millimeters in size (see picture).^[83]

As of 2010, nearly all 5,000 million carats (1,000 tonnes) of synthetic diamonds produced per year are for industrial use. Around 50% of the 133 million carats of natural diamonds mined per year end up in industrial use.^[98]^[102] The cost of mining a natural colorless diamond runs about $40 to $60 per carat, and the cost to produce a synthetic, gem-quality colorless diamond is about $2,500 per carat.^[98] However, a purchaser is more likely to encounter a synthetic when looking for a fancy-colored diamond because nearly all synthetic diamonds are fancy-colored, while only 0.01% of natural diamonds are.

Simulants

Main article: Diamond simulant

A round sparkling, clear gemstone with many facets.

Gem-cut synthetic silicon carbide set in a ring

A diamond simulant is a non-diamond material that is used to simulate the appearance of a diamond, and may be referred to as diamante. Cubic zirconia is the most common. The gemstone Moissanite (silicon carbide) can be treated as a diamond simulant, though more costly to produce than cubic zirconia. Both are produced synthetically.^[104]

Enhancements

Main article: Diamond enhancement

Diamond enhancements are specific treatments performed on natural or synthetic diamonds (usually those already cut and polished into a gem), which are designed to better the gemological characteristics of the stone in one or more ways. These include laser drilling to remove inclusions, application of sealants to fill cracks, treatments to improve a white diamond's color grade, and treatments to give fancy color to a white diamond.^[105]

Coatings are increasingly used to give a diamond simulant such as cubic zirconia a more "diamond-like" appearance. One such substance is diamond-like carbon—an amorphous carbonaceous material that has some physical properties similar to those of the diamond. Advertising suggests that such a coating would transfer some of these diamond-like properties to the coated stone, hence enhancing the diamond simulant. Techniques such as Raman spectroscopy should easily identify such a treatment.

Identification

Early diamond identification tests included a scratch test relying on the superior hardness of diamond. This test is destructive, as a diamond can scratch diamond, and is rarely used nowadays. Instead, diamond identification relies on its superior thermal conductivity. Electronic thermal probes are widely used in the gemological centers to separate diamonds from their imitations. These probes consist of a pair of battery-powered thermistors mounted in a fine copper tip. One thermistor functions as a heating device while the other measures the temperature of the copper tip: if the stone being tested is a diamond, it will conduct the tip's thermal energy rapidly enough to produce a measurable temperature drop. This test takes about 2–3 seconds.^[107]

Whereas the thermal probe can separate diamonds from most of their simulants, distinguishing between various types of diamond, for example synthetic or natural, irradiated or non-irradiated, etc., requires more advanced, optical techniques. Those techniques are also used for some diamonds simulants, such as silicon carbide, which pass the thermal conductivity test. Optical techniques can distinguish between natural diamonds and synthetic diamonds. They can also identify the vast majority of treated natural diamonds.^[108] "Perfect" crystals (at the atomic lattice level) have never been found, so both natural and synthetic diamonds always possess characteristic imperfections, arising from the circumstances of their crystal growth, that allow them to be distinguished from each other.^[109]

Laboratories use techniques such as spectroscopy, microscopy and luminescence under shortwave ultraviolet light to determine a diamond's origin.^[108] They also use specially made instruments to aid them in the identification process. Two screening instruments are the DiamondSure and the DiamondView, both produced by the DTC and marketed by the GIA.^[110]

Several methods for identifying synthetic diamonds can be performed, depending on the method of production and the color of the diamond. CVD diamonds can usually be identified by an orange fluorescence. D-J colored diamonds can be screened through the Swiss Gemmological Institute's^[111] Diamond Spotter. Stones in the D-Z color range can be examined through the DiamondSure UV/visible spectrometer, a tool developed by De Beers.^[109] Similarly, natural diamonds usually have minor imperfections and flaws, such as inclusions of foreign material, that are not seen in synthetic diamonds.

Screening devices based on diamond type detection can be used to make a distinction between diamonds that are certainly natural and diamonds that are potentially synthetic. Those potentially synthetic diamonds require more investigation in a specialized lab. Examples of commercial screening devices are D-Screen (WTOCD / HRD Antwerp) and Alpha Diamond Analyzer (Bruker / HRD Antwerp).

Stolen diamonds

Occasionally large thefts of diamonds take place. In February 2013 armed robbers carried out a raid at Brussels Airport and escaped with gems estimated to be worth $50m (£32m; 37m euros). The gang broke through a perimeter fence and raided the cargo hold of a Swiss-bound plane. The gang have since been arrested and large amounts of cash and diamonds recovered.^[112]

The identification of stolen diamonds presents a set of difficult problems. Rough diamonds will have a distinctive shape depending on whether their source is a mine or from an alluvial environment such as a beach or river - alluvial diamonds have smoother surfaces than those that have been mined. Determining the provenance of cut and polished stones is much more complex.

The Kimberley Process was developed to monitor the trade in rough diamonds and prevent their being used to fund violence. Before exporting, rough diamonds are certificated by the government of the country of origin. Some countries, such as Venezuela, are not party to the agreement. The Kimberley Process does not apply to local sales of rough diamonds within a country.

Diamonds may be etched by laser with marks invisible to the naked eye. Lazare Kaplan, a US-based company, developed this method. However, whatever is marked on a diamond can readily be removed.

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the history of Diamond

history of Diamond

History

Natural history

Formation in cratons

Space diamonds

Transport from mantle

Material properties

Hardness

Electrical conductivity

Surface property

Chemical stability

Color

Identification

Industry

Gem-grade diamonds

Cutting

Marketing

Industrial-grade diamonds

Mining

Political issues

Synthetics, simulants, and enhancements

Synthetics

Simulants

Enhancements

Identification

Stolen diamonds

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