What types of diamonds are there?
Diamond type
Diamond type is a method of scientifically classifying diamonds by the level and type of their chemical impurities. Diamonds are separated into four types: Type Ia, Type Ib, Type IIa, and Type IIb. The impurities measured are at the atomic level within the crystal lattice of carbon atoms and so, unlike inclusions, require an infrared spectrometer to detect.
Diamond cut
There are several older modified brilliant cuts of uncertain age that, while no longer widely used, are notable for history's sake. They are all round in outline and modify the standard round brilliant by adding facets and changing symmetry, either by dividing the standard facets or by placing new ones in different arrangements. These cuts include: the "King" and "Magna" cuts, both developed by New York City firms, with the former possessing 86 facets and 12-fold symmetry and the latter with 102 facets and 10-fold symmetry; the "High-Light" cut, developed by Belgian cutter M. Westreich, with 16 additional facets divided equally between the crown and pavilion; and the "Princess 144", introduced in the 1960s, with 144 facets and 8-fold symmetry. Not to be confused with the mixed "Princess" cut, the Princess 144 cut makes for a lively stone with good scintillation; the extra facets are cut under the girdle rather than subdivided. The extra care required for these sub-girdle facets benefits the finished stone by mitigating girdle irregularity and bearding (hairline fracturing).
Today, with the increased understanding of light dynamics and diamond cutting, many companies have developed new, modified round brilliant cut diamonds. If designed correctly, these extra facets of the modified round brilliant could benefit the overall beauty of a diamond, such as in 91 facet diamonds.
Diamonds as an investment
Diamonds in larger sizes are rare, and their price is dependent on the individual features of the diamond. Fashion and marketing aspects can also cause fluctuations in price. This makes it difficult to establish a uniform and readily understood pricing system. Martin Rapaport produces the Rapaport Diamond Report, which lists prices for polished diamonds. The Rapaport Diamond Report is relatively expensive to subscribe to and, as such, is not readily available to consumers and investors. Each week, there are matrices of diamond prices for various shapes of brilliant cut diamonds, by colour and clarity within size bands. The price matrix for brilliant cuts alone exceeds 1,400 entries, and even this is achieved only by grouping some grades together. There are considerable price shifts near the edges of the size bands, so a stone may list at $5,500 per carat = $2,695, while a stone of similar quality lists at $7,500 per carat = $3,750. This difference seems surprising, but in reality stones near the top of a size band (or rarer fancy coloured varieties) tend to be uprated slightly. Some of the price jumps are related to marketing and consumer expectations. For example, a buyer expecting a diamond solitaire engagement ring may be unwilling to accept a diamond.
Brown diamonds
Brown diamonds are the most common color variety of natural diamonds. In most mines, brown diamonds account for 15% of production. The brown color makes them less attractive as gemstones because of the reduced glimmer, and most are used for industrial purposes. However, improved marketing programs, especially in Australia and the United States, have resulted in brown diamonds becoming valued as gemstones and even referred to as "chocolate diamonds".
Pink diamond
The same four basic parameters that govern the grading of all gemstones are used to grade pink diamonds–the four Cs of connoisseurship: "color", "clarity," "cut" and "carat weight". Color is considered the absolute most important criterion in grading a pink diamond and determining its value. However, size is an important consideration in a pink diamond's value. The larger a pink diamond, and the better its color, the more valuable it will be.
One of the most famous pink diamonds is the Pink Star — at 59.60-carats, this type IIa diamond is the largest vivid pink diamond in the world. In 2014, auction buyer was unable to pay the promised sum and was subsequently forced to default on its purchase. Among famous pink diamonds; the Daria-i-Noor is the largest pink diamond in the world, measured at 182 carats; together with the Noor-ul-Ain, it is the oldest known pink diamond, both belonging to the Iranian crown jewels.
Material properties of diamond
Solid foreign crystals are commonly present in diamond. They are mostly minerals, such as olivine, garnets, ruby, and many others. These and other inclusions, such as internal fractures or "feathers", can compromise the structural integrity of a diamond. Cut diamonds that have been enhanced to improve their clarity via glass infilling of fractures or cavities are especially fragile, as the glass will not stand up to ultrasonic cleaning or the rigors of the jeweler's torch. Fracture-filled diamonds may shatter if treated improperly.
Red diamond
A red diamond is a diamond which displays red color and exhibits the same mineral properties as colorless diamonds. Red diamonds are commonly known as the most expensive and the rarest diamond color in the world, even more so than pink diamonds or blue diamonds. Red diamonds, just like pink diamonds are greatly debated as to the source of their color, but the gemological community most commonly attributes both colors to gliding atoms in the diamond’s structure as it undergoes enormous pressure during its formation. 
Red diamonds are among the 12 colors of fancy color diamonds, and are the most expensive price per carat. They will typically run in the hundreds of thousands of dollars per carat range. Since they are the rarest color, it is difficult to find them in large sizes, and they are mostly found in sizes less than 1 carat. Red diamonds only exist with one color intensity, Fancy, although their clarities can range from Flawless to Included, just like white diamonds. The largest and most flawless red diamond is the 5.11 carat Fancy Red Moussaieff Red Diamond, which has internally flawless clarity.
Crystallographic defects in diamond
The symmetry of defects in crystals is described by the point groups. They differ from the space groups describing the symmetry of crystals by absence of translations, and thus are much fewer in number. In diamond, only defects of the following symmetries have been observed thus far: tetrahedral (T), tetragonal (D), trigonal (D,C), rhombic (C), monoclinic (C, C, C) and triclinic (C or C).
Diamond color
As the diamond trade developed, early diamond grades were introduced by various parties in the diamond trade. Without any co-operative development these early grading systems lacked standard nomenclature, and consistency. Some early grading scales were; "I", "II", "III"; "A", "AA", "AAA"; "A", "B", "C". Numerous terms developed to describe diamonds of particular colors: "golconda", "river", "jagers", "cape", "blue white", "fine white", "gem blue", "brown", etc.
Carbon
Only a very small fraction of the diamond ore consists of actual diamonds. The ore is crushed, during which care has to be taken in order to prevent larger diamonds from being destroyed in this process and subsequently the particles are 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, the separation was done with grease belts; diamonds have a stronger tendency to stick to grease than the other minerals in the ore.
Material properties of diamond
Cape series (Ia) diamonds have a visible absorption spectrum (as seen through a direct-vision spectroscope) consisting of a fine line in the violet at 415.5 nm; however, this line is often invisible until the diamond has been cooled to very low temperatures. Associated with this are weaker lines at 478 nm, 465 nm, 452 nm, 435 nm, and 423 nm.
All those lines are labeled as N3 and N2 optical centers and associated with a defect consisting of three nitrogen atoms bordering a vacancy. Other stones show additional bands: brown, green, or yellow diamonds show a band in the green at 504 nm (H3 center, see above), sometimes accompanied by two additional weak bands at 537 nm and 495 nm (H4 center, a large complex presumably involving 4 substitutional nitrogen atoms and 2 lattice vacancies). Type IIb diamonds may absorb in the far red due to the substitutional boron, but otherwise show no observable visible absorption spectrum.
Metallic dragon
Metallic dragon is a classification of dragon found in the role playing game "Dungeons & Dragons". In this setting metallic dragons are of good alignment. Bahamut is the deity of good-aligned dragons and metallic dragons, and currently the only known Platinum dragon in existence. Metallic dragons have played a large role in D&D's various monster compilation books, and for most of the game's history five main types - brass, copper, bronze, silver, and gold - were presented as roughly analogous to the five types of chromatic dragons. The fourth edition of the game's second "Monster Manual" substituted iron and adamantine dragons for brass and bronze, and released the latter dragons in a later book alongside cobalt, mercury, mithral, orium, and steel dragons.
Diamond color
Type II diamonds have no measurable nitrogen impurities. Type II diamonds absorb in a different region of the infrared, and transmit in the ultraviolet below , unlike Type I diamonds. They also have differing fluorescence characteristics, but no discernible visible absorption spectrum. Type IIa diamond can be colored "pink", "red", or "brown" due to structural anomalies arising through "plastic deformation" during crystal growth—these diamonds are rare (1.8% of gem diamonds), but constitute a large percentage of Australian production. Type IIb diamonds, which account for 0.1% of gem diamonds, are usually light "blue" due to scattered boron within the crystal matrix; these diamonds are also semiconductors, unlike other diamond types (see Electrical properties of diamond). However, a blue-grey color may also occur in Type Ia diamonds and be unrelated to boron. Also not restricted to type are "green" diamonds, whose color is caused by GR1 color centers in the crystal lattice produced by exposure to varying quantities of radiation.
Diamond willow
There are at least six different species that have been identified as being susceptible to diamonding, including "Salix bebbiana", the most common diamond willow, plus "S. pseudomonticola", "S. arbusculoides", "S. discolor", "S. scouleriana", and "S. alaxensis".
Diamond (gemstone)
Most diamonds used as gemstones are basically transparent with little tint, or "white diamonds". The most common impurity, nitrogen, replaces a small proportion of carbon atoms in a diamond's structure and causes a yellowish to brownish tint. This effect is present in almost all white diamonds; in only the rarest diamonds is the coloration from this effect undetectable. The GIA has developed a rating system for color in white diamonds, from D to Z (with D being "colorless" and Z having a bright yellow coloration), which has been widely adopted in the industry and is universally recognized, superseding several older systems. The GIA system uses a benchmark set of natural diamonds of known color grade, along with standardized and carefully controlled lighting conditions. Diamonds with higher color grades are rarer, in higher demand, and therefore more expensive, than lower color grades. Oddly enough, diamonds graded Z are also rare, and the bright yellow color is also highly valued. Diamonds graded D–F are considered "colorless", G–J are considered "near-colorless", K–M are "slightly colored". N–Y usually appear light yellow or brown.
List of largest rough diamonds
This is a partial list of the largest non-synthetic diamonds with a rough stone (uncut) weight of over 200 carats (40 grams). The list is not intended to be complete – e.g., the Cullinan (formerly Premier) mine alone has produced 135 diamonds larger than 200 carats since mining commenced.
List of gemstones by species
There are over 300 types of minerals that have been used as gemstones. These include:
Gemstones in the Bible
Aben-Esra and Abarbanel translate "yhlm" as "diamond"; but "yhlm" was demonstrated above to be beryl. Diamond is made up of pure carbon, mostly of a white transparent colour, but sometimes tinted. White diamond is often regarded as the most precious because of its beauty and rarity.
Diamond (gemstone)
Today, the round brilliant is still the most popular diamond shape for an engagement ring. More than 60 percent of diamonds on the market are brilliants.
Diamond color
The majority of diamonds that are mined are in a range of pale yellow or brown color that is termed the "normal color range". Diamonds that are of intense yellow or brown, or any other color are called "fancy color" diamonds. Diamonds that are of the very highest purity are totally colorless, and appear a bright white. The degree to which diamonds exhibit body color is one of the four value factors by which diamonds are assessed. Diamonds have a color grading system that refers to the absence of color. This system goes from D to Z. The more colorless a diamond is, the rarer and more valuable it is because it appears white and brighter to the eye.
Diamond clarity
Diamonds become increasingly rare when considering higher clarity gradings. Only about 20% of all diamonds mined have a clarity rating high enough for the diamond to be considered appropriate for use as a gemstone; the other 80% are relegated to industrial use. Of that top 20%, a significant portion contains an inclusion or inclusions that are visible to the naked eye upon close inspection. Those that do not have a visible inclusion when the gem is examined approximately 6 inches from the naked eye are known as "eye-clean", although visible inclusions can sometimes be hidden under the setting in a piece of jewelry. The most expensive gem diamonds fall within the VS and SI grades with FL, IF, and even VVS stones commanding significant premiums. FL and IF stones are sometimes referred to as "museum quality" or "investment grade" to denote their rarity although the term "investment grade" is misleading as diamonds have historically been illiquid and questionable stores of value.
Blue diamond
In gemology, color is divided into three components: "hue", "saturation" and "tone". Blue diamonds occur in hues ranging from green-blue to gray-blue, with the primary hue necessarily being blue. Green and gray are the normal secondary hues that can be found in blue diamonds. Blue diamonds are considered most beautiful and valuable when there is no secondary color present but rather are a pure blue color. However, a pure blue diamond of light color may be considered less valuable than a green-blue or gray-blue diamond whose color is more vivid. The characteristic of color is very complex in blue diamonds for this reason. Most pure blue diamonds are Type IIb, meaning they contain either very few or a complete lack of nitrogen impurities. Type Ia blue stones contain a secondary hue and get their color from the presence of hydrogen.
Diamond cubic
The diamond cubic crystal structure is a repeating pattern of 8 atoms that certain materials may adopt as they solidify. While the first known example was diamond, other elements in group 14 also adopt this structure, including α-tin, the semiconductors silicon and germanium, and silicon/germanium alloys in any proportion.
Ballas
Ballas or shot bort is a term used in the diamond industry to refer to shards of non-gem-grade/quality diamonds. It comprises small diamond crystals that are concentrically arranged in rough spherical stones with a fibrous texture. Ballas is hard, tough, and difficult to cleave. It is mostly found in Brazil and South Africa.
Diamond
Because the arrangement of atoms in diamond is extremely rigid, few types of impurity can contaminate it (two exceptions being boron and nitrogen). Small numbers of defects or impurities (about one per million of lattice atoms) color diamond blue (boron), yellow (nitrogen), brown (defects), green (radiation exposure), purple, pink, orange or red. Diamond also has relatively high optical dispersion (ability to disperse light of different colors).
Diamond (gemstone)
In the wholesale trade of gem diamonds, carat is often used in denominating lots of diamonds for sale. For example, a buyer may place an order for of , D–F, VS2-SI1, excellent cut diamonds, indicating a wish to purchase 200 diamonds ( total mass) of those approximate characteristics. Because of this, diamond prices (particularly among wholesalers and other industry professionals) are often quoted per carat, rather than per stone.
Diamond (gemstone)
Diamonds which show very little traces of color are graded as G or H color diamonds. Slightly colored diamonds are graded as I or J or K color. A diamond can be found in any color in addition to colorless. Some of the colored diamonds, such as pink, are very rare.
Dymalloy
Similar alloys are possible with the metal phase consisting of one or more of silver, copper, gold, aluminium, magnesium, and zinc. The carbide-forming metal can be selected from titanium, zirconium, hafnium, vanadium, niobium, tantalum, and chromium, where Ti, Zr, and Hf are preferable. The amount of carbide-forming metal must be sufficient to coat at least 25% of the diamond grains, as otherwise the bonding is insufficient, the heat transfer between matrix and diamond grains is weak which leads to loss of effectivity towards the level of the matrix metal alone, and the material may deform at higher temperatures, and must be low in order to prevent formation of too thick carbide layer that would hinder heat transfer. The volume of diamond should be higher than 30 vol.%, as lower ratio does not provide significant increase of thermal conductivity, and lower than 70 vol.% as higher ratio of diamond makes thermal expansion matching to semiconductors difficult. The grains should also be completely surrounded with metal, to avoid deformation due to different thermal expansion coefficients between diamond and metal; the carbide coating assists with this.
Diamond (gemstone)
Diamonds are used in engagement rings. The practice is documented among European aristocracy as early as the 15th century, though ruby and sapphire were more desirable gemstones. The modern popularity of diamonds was largely created by De Beers Consolidated Mines Ltd., which established the first large-scale diamonds mines in South Africa. Through an advertising campaign beginning in the 1930s and continuing into the mid-20th century, De Beers made diamonds into a key part of the betrothal process and a coveted symbol of status. The diamond's high value has been the driving force behind dictators and revolutionary entities, especially in Africa, using slave and child labor to mine blood diamonds to fund conflicts. Though popularly believed to derive its value from its rarity, gem-quality diamonds are quite common compared to rare gemstones such as alexandrite, and annual global rough diamond production is estimated to be about .
Diamond (gemstone)
The most familiar usage of diamonds today is as gemstones used for adornment—a usage which dates back into antiquity. The dispersion of white light into spectral colors is the primary gemological characteristic of gem diamonds. In the twentieth century, gemologists have developed methods of grading diamonds and other gemstones based on the characteristics most important to their value as a gem. Four characteristics known informally as the "four Cs" are now commonly used as the basic descriptors of diamonds: carat, cut, color, and clarity. This system was developed by Gemological Institute of America in 1953 as internationally recognized standard to evaluate diamonds characteristics.
Allotropes of carbon
The market for industrial-grade diamonds operates much differently from its gem-grade counterpart. Industrial diamonds are valued mostly for their hardness and heat conductivity, making many of the gemological characteristics of diamond, including clarity and color, mostly irrelevant. This helps explain why 80% of mined diamonds (equal to about 100 million carats or 20 tonnes annually) are unsuitable for use as gemstones and known as "bort", are destined for industrial use. In addition to mined diamonds, synthetic diamonds found industrial applications almost immediately after their invention in the 1950s; another 400 million carats (80 tonnes) of synthetic diamonds are produced annually for industrial use, which is nearly four times the mass of natural diamonds mined over the same period.
Diamond color
Fancy diamonds are valued using different criteria than those used for regular diamonds. When the color is rare, the more intensely colored a diamond is, the more valuable it becomes. Another factor that affects the value of Fancy-Colored diamonds is fashion trends. For example, pink diamonds fetched higher prices after Jennifer Lopez received a pink diamond engagement ring. Traditional industrial use and low-grade quality has not stopped creative merchants, such as Le Vian, from marketing dark brown diamonds as so-called "chocolate diamonds".
Diamond-like carbon
DLC exists in seven different forms. All seven contain significant amounts of sp hybridized carbon atoms. The reason that there are different types is that even diamond can be found in two crystalline polytypes. The more common one has its carbon atoms arranged in a cubic lattice, while the less common one, lonsdaleite, has a hexagonal lattice. By mixing these polytypes in various ways at the nanoscale level of structure, DLC coatings can be made that at the same time are amorphous, flexible, and yet purely sp bonded "diamond". The hardest, strongest, and slickest is such a mixture, known as tetrahedral amorphous carbon (ta-C). For example a coating of only 2 μm thickness of "ta-C" increases the resistance of common (e.g., type 304) stainless steel against abrasive wear, changing its lifetime in such service from one week to 85 years. Such "ta-C" can be considered to be the "pure" form of DLC, since it consists only of sp bonded carbon atoms. Fillers such as hydrogen, graphitic sp carbon, and metals are used in the other 6 forms to reduce production expenses or to impart other desirable properties.
Diamond simulant
A diamond simulant, diamond imitation or imitation diamond is an object or material with gemological characteristics similar to those of a diamond. Simulants are distinct from synthetic diamonds, which are actual diamonds having the same material properties as natural diamonds. Enhanced diamonds are also excluded from this definition. A diamond simulant may be artificial, natural, or in some cases a combination thereof. While their material properties depart markedly from those of diamond, simulants have certain desired characteristics—such as dispersion and hardness—which lend themselves to imitation. Trained gemologists with appropriate equipment are able to distinguish natural and synthetic diamonds from all diamond simulants, primarily by visual inspection.
Gemstone
The traditional classification in the West, which goes back to the ancient Greeks, begins with a distinction between "precious" and "semi-precious"; similar distinctions are made in other cultures. In modern use the precious stones are diamond, ruby, sapphire and emerald, with all other gemstones being semi-precious. This distinction reflects the rarity of the respective stones in ancient times, as well as their quality: all are translucent with fine color in their purest forms, except for the colorless diamond, and very hard, with hardnesses of 8 to 10 on the Mohs scale. Other stones are classified by their color, translucency and hardness. The traditional distinction does not necessarily reflect modern values, for example, while garnets are relatively inexpensive, a green garnet called tsavorite can be far more valuable than a mid-quality emerald. Another unscientific term for semi-precious gemstones used in art history and archaeology is hardstone. Use of the terms 'precious' and 'semi-precious' in a commercial context is, arguably, misleading in that it deceptively implies certain stones are intrinsically more valuable than others, which is not necessarily the case.
Extraterrestrial diamonds
Although diamonds on Earth are rare, extraterrestrial diamonds (diamonds formed outside of Earth) are very common. Diamonds not much larger than molecules are abundant in meteorites and some of them formed in stars before the Solar System existed. High pressure experiments suggest large amounts of diamonds are formed from methane on the ice giant planets Uranus and Neptune, while some planets in other solar systems may be almost pure diamond. Diamonds are also found in stars and may have been the first mineral ever to have formed.
Synthetic diamond
Traditionally, the absence of crystal flaws is considered to be the most important quality of a diamond. Purity and high crystalline perfection make diamonds transparent and clear, whereas its hardness, optical dispersion (luster), and chemical stability (combined with marketing), make it a popular gemstone. High thermal conductivity is also important for technical applications. Whereas high optical dispersion is an intrinsic property of all diamonds, their other properties vary depending on how the diamond was created.
Diamond blade
Sintered metal-bonded diamond blades are the most common type of blade. These blades consist of a steel core (the base is steel plate, unlike that of the wires used in diamond wire saws) and "diamond segments", which are made by combining synthetic diamond crystals with metal powder and then sintering them. The diamond segments are also known as the "cutting teeth" of the blade.
Diamond cut
The dominating round brilliant diamonds are not as trendy as they used to be since the market was overcrowded in the last decades of the century Simultaneously, giving a fancy diamond cut as a precious jewel on specific celebrations became a part of tradition. A "Heart cut" diamond has romantic symbolism so it is a common gift for Valentine's Day or wedding anniversary. The "pear-shaped" diamonds look like a drop of water and the shape is suitable for diamond earrings. The most famous shapes are: "Princess, Cushion, Heart, Pear, Marquise, Radiant, Asscher cut, Emerald, Oval."
Extraterrestrial diamonds
It has been proposed that diamonds exist in carbon-rich stars, particularly white dwarfs; and carbonado, a polycrystalline mix of diamond, graphite and amorphous carbon and the toughest natural form of carbon, could come from supernovae and white dwarfs. The largest white dwarf found in the universe so far, BPM 37093, located away in the constellation Centaurus and having a diameter of , may have a diamond core.
Diamond cut
Various forms of the "rose cut" have been in use since the mid-16th century. Like the step cuts, they were derived from older types of cuts. The basic rose cut has a flat base—that is, it lacks a pavilion—and has a crown composed of triangular facets (usually 12 or 24) rising to form a point (there is no table facet) in an arrangement with sixfold rotational symmetry. The so-called "double rose cut" is a variation that adds six kite facets at the margin of the base. The classic rose cut is circular in outline; non-circular variations on the rose cut include the "briolette" (oval), "Antwerp rose" (hexagonal), and "double Dutch rose" (resembling two rose cuts united back-to-back). Rose-cut diamonds are seldom seen nowadays, except in antique jewelry. Like the older style brilliants and step cuts, there is a growing demand for the purpose of repairing or reproducing antique pieces.
Diamond firetail
There are few mutations in the diamond firetail, however, one mutation produces an orange tail, instead of the fiery red, in this case the bird is known as the yellow diamond. Other mutations are the pied diamond which has splashes of white, the white diamond, and the fawn diamond.
Pearl
Pearls come in eight basic shapes: round, semi-round, button, drop, pear, oval, baroque, circled and double bouldered. Perfectly round pearls are the rarest and most valuable shape. Semi-rounds are also used in necklaces or in pieces where the shape of the pearl can be disguised to look like it is a perfectly round pearl. Button pearls are like a slightly flattened round pearl and can also make a necklace, but are more often used in single pendants or earrings where the back half of the pearl is covered, making it look like a larger, rounder pearl.
Argyle diamond mine
The diamonds produced at the Argyle diamond mine are of an average low quality. Only 5% of mined diamonds are of gem quality, compared to a worldwide average of 20% (Author Janine Roberts contends that the "near-gem" quality rating is subjective and misleading because these diamonds can be cut into gems if desired.); of the remaining 95%, they are about evenly split between classifications of "near gem quality" and industrial grade; 80% of Argyle diamonds are brown, followed by 16% yellow, 2% white, 2% grey, and less than 1% pink and green. Despite the low production volume of pink and red diamonds, the Argyle mine is the only reliable source in the world, producing 90 to 95% of all pink and red diamonds. Most Argyle diamonds are classified as type 1a (see material properties of diamond), and have low levels of nitrogen impurities, their colour resulting instead from structural defects of the crystal lattice. Argyle diamonds tend to fluoresce blue or dull green under ultraviolet light, and blue-white under X-ray radiation. The most common inclusion is unconverted graphite, followed by crystalline inclusions of orange garnet, pyroxene, and olivine.
Nanodiamond
Nanodiamonds or diamond nanoparticles (medical use) are diamonds with a size below 1 micrometre. They can be produced by impact events such as an explosion or meteoritic impacts. Because of their inexpensive, large-scale synthesis, potential for surface functionalization, and high biocompatibility, nanodiamonds are widely investigated as a potential material in biological and electronic applications and quantum engineering.
List of diamonds
A number of large diamonds have gained fame, both as examples of the beautiful nature of diamonds and because of the famous people who wore, bought, and sold them. A partial list of famous diamonds in history follows.
Crystallographic defects in diamond
Imperfections in the crystal lattice of diamond are common. Such crystallographic defects in diamond may be the result of lattice irregularities or extrinsic substitutional or interstitial impurities, introduced during or after the diamond growth. The defects affect the material properties of diamond and determine to which type a diamond is assigned; the most dramatic effects are on the diamond color and electrical conductivity, as explained by the electronic band structure.
Pink diamond
Pink diamonds belong to a subcategory of diamonds called fancy color diamonds, the generic name for all diamonds that exhibit any sort of color. Pink diamonds range from flawless to included, just as white diamonds. Several pink diamonds with internally flawless clarity have been discovered, but only one is known to be completely flawless, the Pink Star (which was shortly renamed the Pink Dream until it diverted to Sotheby's).
Carbonado
Carbonado, commonly known as the "black diamond", is the toughest form of natural diamond. It is an impure form of polycrystalline diamond consisting of diamond, graphite, and amorphous carbon. It is found primarily in alluvial deposits in the Central African Republic and in Brazil. Its natural colour is black or dark grey, and it is more porous than other diamonds.
Diamonds (suit)
Normally diamonds are red in colour. They can however be depicted in blue, which is the case for example in bridge (where it is one of the two minor suits along with Clubs).
Red diamond
The color in red diamonds is assessed according to its hue and saturation. Red diamonds can occur with secondary colors, such as brown-red, orange-red, or purple-red, but red is not a modifying color for any other diamond color. Additionally, red diamonds never appear with a tertiary modifying color, as is the case in other diamond colors. A pure red diamond is ideal but an even rarer find than a red with a secondary color. Like with other diamond colors, a purely red diamond will fetch a higher per carat price than one with a secondary hue. Brownish red and Orangey red diamonds are generally considered inferior to Purplish Red diamonds and are priced accordingly. All of these colors run upwards of $400,000 per carat, but a pure red diamond can cost significantly more per carat. Few colors of fancy color diamonds are characterized by having a singular color intensity. This phenomenon only exists with three colors: black diamonds, white diamonds, and red diamonds. Since the source of the red in red diamonds is considered to be a hyper-concentrated occurrence of pink, this would actually make red the darkest shade of pink possible, which is why it is only able to appear in one intensity. Red diamonds will only be graded Fancy Red, Fancy Brownish Red, Fancy Purplish Red, or Fancy Orangey Red. An easy way to tell whether a red diamond is fake is if the seller is offering it with an intensity grade like other diamond colors (Fancy Light, Fancy Intense, Fancy Vivid etc.). There are so few red diamonds that the GIA records show that over a 30 year period from 1957–1987, not a single GIA lab report with the term “red” was issued. Some diamond polishers have achieved a GIA grading of Fancy Red for a diamond by re-polishing a Fancy Deep Pink diamond, although this is very hard to accomplish and has only been successfully completed less than a handful of times.
Material properties of diamond
Diamonds crystallize in the diamond cubic crystal system (space group Fdm) and consist of tetrahedrally, covalently bonded carbon atoms. A second form called lonsdaleite, with hexagonal symmetry, has also been found, but it is extremely rare and forms only in meteorites or in laboratory synthesis. The local environment of each atom is identical in the two structures. From theoretical considerations, lonsdaleite is expected to be harder than diamond, but the size and quality of the available stones are insufficient to test this hypothesis. In terms of crystal habit, diamonds occur most often as euhedral (well-formed) or rounded octahedra and twinned, flattened octahedra with a triangular outline. Other forms include dodecahedra and (rarely) cubes. There is evidence that nitrogen impurities play an important role in the formation of well-shaped euhedral crystals. The largest diamonds found, such as the Cullinan Diamond, were shapeless. These diamonds are pure (i.e. type II) and therefore contain little if any nitrogen.
Diamond cut
The most popular of diamond cuts is the modern round brilliant, whose facet arrangements and proportions have been perfected by both mathematical and empirical analysis. Also popular are the fancy cuts, which come in a variety of shapes, many of which were derived from the round brilliant. A diamond's cut is evaluated by trained graders, with higher grades given to stones whose symmetry and proportions most closely match the particular "ideal" used as a benchmark. The strictest standards are applied to the round brilliant; although its facet count is invariable, its proportions are not. Different countries base their cut grading on different ideals: one may speak of the "American Standard" or the "Scandinavian Standard" ("Scan. D.N."), to give but two examples.
Diamond cutting
Due to changes in market desirability and popularity, the value of different styles of diamond fluctuate. All diamonds can be recut into new shapes that will increase value at that time in the market and desirability. An example of this is the "marquise" cut diamond which was popular in the 1970s to 1980s. In later decades, jewelers had little success in selling this shape in comparison to other shapes like the oval or pear shape. The "marquise" can be cut into an oval diamond by any diamond cutter with a loss of 5-10% in total weight. For example, a 1.10 carat marquise shape would be a 1.00 oval cut diamond by rounding the sharp points and creating an oval which currently in the market has a much greater desirability and resale value. The same marquise shape also could become a pear shape instead by only trimming and rounding the side which will be turned into the base of the pear shape.
Mineral
Differences in crystal structure and chemistry greatly influence other physical properties of the mineral. The carbon allotropes diamond and graphite have vastly different properties; diamond is the hardest natural substance, has an adamantine lustre, and belongs to the isometric crystal family, whereas graphite is very soft, has a greasy lustre, and crystallises in the hexagonal family. This difference is accounted for by differences in bonding. In diamond, the carbons are in sp hybrid orbitals, which means they form a framework where each carbon is covalently bonded to four neighbours in a tetrahedral fashion; on the other hand, graphite is composed of sheets of carbons in sp hybrid orbitals, where each carbon is bonded covalently to only three others. These sheets are held together by much weaker van der Waals forces, and this discrepancy translates to large macroscopic differences.
Material properties of diamond
More than 20 other minerals have higher dispersion (that is difference in refractive index for blue and red light) than diamond, such as titanite 0.051, andradite 0.057, cassiterite 0.071, strontium titanate 0.109, sphalerite 0.156, synthetic rutile 0.330, cinnabar 0.4, etc. (see dispersion). However, the combination of dispersion with extreme hardness, wear and chemical resistivity, as well as clever marketing, determines the exceptional value of diamond as a gemstone.
Diamonds exhibit fluorescence, that is, they emit light of various colors and intensities under long-wave ultraviolet light (365 nm): Cape series stones (type Ia) usually fluoresce blue, and these stones may also phosphoresce yellow, a unique property among gemstones. Other possible long-wave fluorescence colors are green (usually in brown stones), yellow, mauve, or red (in type IIb diamonds). In natural diamonds, there is typically little if any response to short-wave ultraviolet, but the reverse is true of synthetic diamonds. Some natural type IIb diamonds phosphoresce blue after exposure to short-wave ultraviolet. In natural diamonds, fluorescence under X-rays is generally bluish-white, yellowish or greenish. Some diamonds, particularly Canadian diamonds, show no fluorescence.
Dragon (Dungeons &amp; Dragons)
Types
Diamond (gemstone)
The finest quality as per color grading is totally colorless, which is graded as D color diamond across the globe, meaning it is absolutely free from any color. The next grade has a very slight trace of color, which can be observed by any expert diamond valuer/grading laboratory. However, when studded in jewellery these very light colored diamonds do not show any color or it is not possible to make out color shades. These are graded as E color or F color diamonds.
Napoleon Diamond Necklace
The Napoleon Diamond Necklace consists of 28 mine cut diamonds set into a single thread, with a fringe of alternating pendeloque and briolettes diamond cuts. The five pear-shaped pendoloques are each mounted below a small brilliant cut diamond. The four ovaline pendeloques are mounted above designs which incorporate 23 brilliant cut diamonds each. Each briolette mounting is set with 12 rose cut diamonds.
Diamond simulant
In order to be considered for use as a diamond simulant, a material must possess certain diamond-like properties. The most advanced artificial simulants have properties which closely approach diamond, but all simulants have one or more features that clearly and (for those familiar with diamond) easily differentiate them from diamond. To a gemologist, the most important of differential properties are those that foster non-destructive testing; most of these are visual in nature. Non-destructive testing is preferred because most suspected diamonds are already cut into gemstones and set in jewelry, and if a destructive test (which mostly relies on the relative fragility and softness of non-diamonds) fails, it may damage the simulant—an unacceptable outcome for most jewelry owners, as even if a stone is not a diamond, it may still be of value.
Gemological Institute of America
The GIA Laboratory provides a variety of gem grading and identification reports. Diamond grading reports for unmounted natural and synthetic diamonds determine their key characteristics: color, clarity, cut and carat weight. GIA issues two types of reports, the more complete being the Diamond Grading Report (a briefer and less expensive version is called a Diamond Dossier). The reports contain a number of measurements, including of carat weight as well as a diagram of where and what types of inclusions are located in the diamond. Diamond grading reports are now demanded by most consumers purchasing diamonds over a certain size, typically for over 0.5 carat (100 mg), and almost always for over 1.0 carat (200 mg), and are considered an important tool in guaranteeing that a diamond is accurately represented to a potential buyer.
Elizabeth Taylor Diamond
There is a supplemental letter from the Gemological Institute of America stating that the diamond has been determined to be a Type IIa diamond. Type IIa diamonds are the most chemically pure type of diamond, and often have exceptional optical transparency. Type IIa diamonds were first identified as originating from India, particularly from the Golconda region, but have since been recovered in all major diamond-producing regions of the world. Famous examples of Type IIa diamonds are the 530.20 carat Cullinan I and the 105.60 carat Koh-i-noor.
The supplemental letter from the GIA is accompanied by a monograph from the Gemological Institute of America which features additional photographs, data collection charts and gemological research which details the rarity of the Elizabeth Taylor Diamond.
Material properties of diamond
Diamond is the allotrope of carbon in which the carbon atoms are arranged in the specific type of cubic lattice called diamond cubic. Diamond is an optically isotropic crystal that is transparent to opaque. Diamond is the hardest naturally occurring material known. Yet, due to important structural weaknesses, diamond's toughness is only fair to good. The precise tensile strength of diamond is unknown, however strength up to 60 GPa has been observed, and it could be as high as 90–225 GPa depending on the crystal orientation. The anisotropy of diamond hardness is carefully considered during diamond cutting. Diamond has a high refractive index (2.417) and moderate dispersion (0.044) properties which give cut diamonds their brilliance. Scientists classify diamonds into four main types according to the nature of crystallographic defects present. Trace impurities substitutionally replacing carbon atoms in a diamond's crystal structure, and in some cases structural defects, are responsible for the wide range of colors seen in diamond. Most diamonds are electrical insulators but extremely efficient thermal conductors. Unlike many other minerals, the specific gravity of diamond crystals (3.52) has rather small variation from diamond to diamond.
Diamondoid
In chemistry, diamondoids are variants of the carbon cage molecule known as adamantane (CH), the smallest unit cage structure of the diamond crystal lattice. Diamondoids also known as nanodiamonds or condensed adamantanes may include one or more cages (adamantane, diamantane, triamantane, and higher polymantanes) as well as numerous isomeric and structural variants of adamantanes and polymantanes. These diamondoids occur naturally in petroleum deposits and have been extracted and purified into large pure crystals of polymantane molecules having more than a dozen adamantane cages per molecule. These species are of interest as molecular approximations of the diamond cubic framework, terminated with C−H bonds. Cyclohexamantane may be thought of as a nanometer-sized diamond of approximately .
Crystallographic defects in diamond
Diamonds containing boron as a substitutional impurity are termed "type IIb". Only one percent of natural diamonds are of this type, and most are blue to grey. Boron is an acceptor in diamond: boron atoms have one less available electron than the carbon atoms; therefore, each boron atom substituting for a carbon atom creates an electron hole in the band gap that can accept an electron from the valence band. This allows red light absorption, and due to the small energy (0.37 eV) needed for the electron to leave the valence band, holes can be thermally released from the boron atoms to the valence band even at room temperatures. These holes can move in an electric field and render the diamond electrically conductive (i.e., a p-type semiconductor). Very few boron atoms are required for this to happen—a typical ratio is one boron atom per 1,000,000 carbon atoms.
Diamond (gemstone)
Diamonds do not show all of their beauty as rough stones; instead, they must be cut and polished to exhibit the characteristic fire and brilliance that diamond gemstones are known for. Diamonds are cut into a variety of shapes that are generally designed to accentuate these features.
Jacob &amp; Co
Jacob & Co. is also known for its fine jewelry collections, offering unique designs in a variety of styles, including a range of engagement rings and wedding bands for both men and women. The company also designs custom wedding rings, allowing customers to choose diamonds of any shape, size or color. Jacob & Co claims to use the "world's finest and most exclusive gems" for its jewelry such as the pure, colorless Golconda diamonds of India, and rare colored stones from Africa and Brazil. The company purchases diamonds only from countries that are full participants in the Kimberley Process Certification Scheme (KPCS), an international monitoring system created to stem the flow of conflict diamonds, and all diamonds come with Gemological Institute of America authenticity reports.
Gemstone
Gemstones are classified into different "groups", "species", and "varieties". For example, ruby is the red variety of the species corundum, while any other color of corundum is considered sapphire. Other examples are the emerald (green), aquamarine (blue), red beryl (red), goshenite (colorless), heliodor (yellow) and morganite (pink), which are all varieties of the mineral species beryl.
Niquelândia
Although mining is practically all done for nickel, there are also more than 120 types of mineral, such as gold, crystal, platinum, copper, mica, iron, manganese, diamonds, quartz, marble, cobalt, asbestos and even uranium.
Isotopically pure diamond
An isotopical pure diamond is a type of diamond that is composed entirely of one isotope of carbon. Isotopically pure diamonds have been manufactured from either the more common carbon isotope with mass number 12 (abbreviated as C) or the less common C isotope. Compared to natural diamonds that are composed of a mixture of C and C isotopes, isotopically pure diamonds possess improved characteristics such as increased thermal conductivity. Thermal conductivity of diamonds is at a minimum when C and C are in a ratio of 1:1 and reaches a maximum when the composition is 100% C or 100% C.
Engagement ring
In the United States, where engagement rings are worn by women, diamonds have been widely featured in engagement rings since the middle of the 20th century. Solitaire rings have one diamond. The most common setting for engagement rings is the solitaire prong setting, which was popularized by Tiffany & Co. in 1886 and its six-claw prong setting design sold under the "Tiffany setting" trademark. The modern favorite cut for an engagement ring is the brilliant cut, which provides the maximum amount of sparkle to the gemstone. The traditional engagement rings may have different prong settings and bands. Another major category is engagement rings with side stones. Rings with a larger diamond set in the middle and smaller diamonds on the side fit under this category. Three-stone diamond engagement rings, sometimes called "trinity rings" or "trilogy rings", are rings with three matching diamonds set horizontally in a row with the bigger stone placed in the center. The three diamonds on the ring are typically said to represent the couple's past, present, and future, but other people give religious significance to the arrangement.
Diamonds as an investment
Old diamond jewellery in India, specially from the Mughal period, uses unfaceted diamonds. Mughal style jewellery has become popular in India recently featuring uncut diamonds termed "Polki" (which originally referred to a style of cleaving diamonds). The diamonds used in modern polki jewellery are low grade and do not have much investment value, even though polki jewellery can be expensive. The diamonds are backed by silver foil to allow light to reflect. The Kundan jewellery in India uses the same style, but it uses glass instead of diamonds.
Superhard material
Diamond is an allotrope of carbon where the atoms are arranged in a modified version of face-centered cubic ("fcc") structure known as "diamond cubic". It is known for its hardness (see table above) and incompressibility and is targeted for some potential optical and electrical applications. The properties of individual natural diamonds or carbonado vary too widely for industrial purposes, and therefore synthetic diamond became a major research focus.
Hearts and arrows
Hearts and Arrows diamonds are precision-cut variations of the traditional 57 faceted round brilliant cut. They are cut to ideal proportions with good optical symmetry, polish and a specific faceting pattern. When all these factors are present, the result is a repeatable, near perfect pattern of eight symmetrical arrows in the face-up position of the stone (called 'crown') and eight symmetrical hearts when viewed in the table-down position (called 'pavilion').
Diamonds (suit)
The diamond typically has a diamond shape, a parallelogram with four equal sides, placed on one of its points. The sides are sometimes slightly rounded and the four vertices placed in a square, making the sign look like an astroid.
Diamond (gemstone)
A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or "color". However, in reality most gem-sized natural diamonds are imperfect. The color of a diamond may be affected by chemical impurities and/or structural defects in the crystal lattice. Depending on the hue and intensity of a diamond's coloration, a diamond's color can either detract from or enhance its value. For example, most white diamonds are discounted in price as a more yellow hue is detectable, while intense pink or blue diamonds (such as the Hope Diamond) can be dramatically more valuable. The Aurora Diamond Collection displays a spectacular array of naturally colored diamonds, which occur in every color of the rainbow.
Diamond segment
Diamond segments consist of small-size diamonds and metal bond materials. The metal bond materials may include the powders of Cu, Sn, Fe, Ag, Co, Ni, WC, Mo, graphite, etc. The diamonds are mixed with the bond materials, and the mixture is loaded into molds. After hot pressing or cold pressing, sintering, and arc grinding, diamond segments are formed. The metal bond has two basic functions: One is bonding the diamonds to the body of the tool; the other is wearing along with the diamonds' wearing to let the new sharp diamonds be exposed properly.
Kimberlite
Kimberlites are the most important source of primary diamonds. Many kimberlite pipes also produce rich alluvial or eluvial diamond placer deposits. About 6,400 kimberlite pipes have been discovered in the world, of those about 900 have been classified as diamondiferous, and of those just over 30 have been economic enough to diamond mine.
The deposits occurring at Kimberley, South Africa, were the first recognized and the source of the name. The Kimberley diamonds were originally found in weathered kimberlite, which was colored yellow by limonite, and so was called "yellow ground". Deeper workings encountered less altered rock, serpentinized kimberlite, which miners call "blue ground".
Gemstone
In modern times gemstones are identified by gemologists, who describe gems and their characteristics using technical terminology specific to the field of gemology. The first characteristic a gemologist uses to identify a gemstone is its chemical composition. For example, diamonds are made of carbon (C) and rubies of aluminium oxide (). Next, many gems are crystals which are classified by their crystal system such as cubic or trigonal or monoclinic. Another term used is habit, the form the gem is usually found in. For example, diamonds, which have a cubic crystal system, are often found as octahedrons.
Diamond segment
The form of diamond blades' diamond segments may be convex, layered sandwich concave, L-shaped, step-shaped, segmented, side-slotted, etc. There are mainly two purposes to make these forms: one is to increase the blade's capabilities of containing and discharging sawdust, and improve the cooling and lubricating conditions. The other is to reduce the friction between the segments and the material being cut as well as the sawdust, improve the blade's cutting capability, and thus save energy and improve the blade's performance.
Pink Panther jewel
Type II diamonds have almost no nitrogen impurities in them. Their coloration is due to structural anomalies caused by Plastic Deformation during crystal growth. The intense pressure changes the lattice structure of diamonds and leads to the formation of pink, red, and brown diamonds. Only one of the 66 largest diamonds in the world is pink. When Ben Affleck gave Jennifer Lopez a pink diamond solitaire engagement ring, traffic to Web sites that sold pink diamonds increased by around 300 to 400 percent.
Pink diamond
Pink diamond is a type of diamond that has pink color. The source of their pink color is greatly debated in the gemological world but it is most commonly attributed to enormous additional pressure that these diamonds undergo during their formation.
Pentawards
Five levels of awards are given: diamond, platinum, gold, silver, bronze. The diamond award is given to the packaging design which, across all categories, received the highest number of points. The platinum award goes in each of five major categories, to the packaging designs which received the most points in the given category. The gold, silver and bronze awards are given to the best packaging design in each sub-category. The trophies are representations of the Pentawards logo, a circle with a hollow pentagon in the center. They are manufactured with a zinc alloy and after being polished are plated. The "diamond" is a Swarovski crystal. The trophy was designed and engraved by Belgo-American artist Christian Heckscher.
Corundum
Corundum is a crystalline form of aluminium oxide () typically containing traces of iron, titanium, vanadium and chromium. It is a rock-forming mineral. It is also a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. Corundum has two primary gem varieties, ruby and sapphire. Rubies are red due to the presence of chromium, and sapphires exhibit a range of colors depending on what transition metal is present. A rare type of sapphire, padparadscha sapphire, is pink-orange.
Diamond
Most natural diamonds have ages between 1 billion and 3.5 billion years. Most were formed at depths between in the Earth's mantle, although a few have come from as deep as . Under high pressure and temperature, carbon-containing fluids dissolved minerals and replaced them with diamonds. Much more recently (tens to hundreds of million years ago), they were carried to the surface in volcanic eruptions and deposited in igneous rocks known as kimberlites and lamproites.
Diamonds as an investment
Diamonds of smaller sizes are traded in parcels of similar stones, called 'melee', after the French word for mix. Generally diamonds of exactly similar size, cut, shape, color and clarity are used in a single piece of diamond jewelry. If not, the stones would not match and the piece would not sell. Small recycled diamonds are treated differently from large individual stones. A single small diamond has limited value by itself. It is only of use if it can be matched with other similar diamonds, reset into jewelry and sold to a customer, thereby creating value. Small recycled diamonds need to be sorted, recut and resold to manufacturers in large parcels to allow them to pick matching stones to set in jewelry.
Diamond (gemstone)
Because of their extraordinary physical properties, diamonds have been used symbolically since near the time of their first discovery. Perhaps the earliest symbolic use of diamonds was as the eyes of Hindu devotional statues. In Hinduism Indra uses Vajrayudham or the thunderbolt as his primary weapon. "Vajra" is the word for diamond and "ayudham" means weapon in Sanskrit. Another name for it was "Agira" which means "fire" or the "sun". In fact there are 14 names counted to be given to a diamond in traditional Hinduism.
Diamond plate
Diamond plate, also known as checker plate, tread plate and Durbar floor plate, is a type of metal stock with a regular pattern of raised diamonds or lines on one side, with the reverse side being featureless. Diamond plate is usually steel, stainless steel or aluminum. Steel types are normally made by hot rolling, although modern manufacturers also make a raised and pressed diamond design.
Diamond blade
A diamond blade is a saw blade which has diamonds fixed on its edge for cutting hard or abrasive materials. There are many types of diamond blade, and they have many uses, including cutting stone, concrete, asphalt, bricks, coal balls, glass, and ceramics in the construction industry; cutting semiconductor materials in the IT industry; and cutting gemstones, including diamonds, in the gem industry.
Gemstone
Synthetic, cultured or lab-created gemstones are not imitations. For example, diamonds, rubies, sapphires and emeralds have been manufactured in labs to possess identical chemical and physical characteristics to the naturally occurring variety. Synthetic (lab created) corundum, including ruby and sapphire, is very common and costs much less than the natural stones. Smaller synthetic diamonds have been manufactured in large quantities as industrial abrasives, although larger gem-quality synthetic diamonds are becoming available in multiple carats.
Diamond color
Type I diamonds have nitrogen atoms as the main impurity, commonly at a concentration of 0.1%. If the nitrogen atoms are in pairs they do not affect the diamond's color; these are Type IaA. If the nitrogen atoms are in large even-numbered aggregates they impart a yellow to brown tint (Type IaB). About 98% of gem diamonds are type Ia, and most of these are a mixture of IaA and IaB material: these diamonds belong to the "Cape series", named after the diamond-rich region formerly known as Cape Province in North Africa, whose deposits are largely Type Ia. If the nitrogen atoms are dispersed throughout the crystal in isolated sites (not paired or grouped), they give the stone an intense "yellow" or occasionally "brown" tint (Type Ib); the rare "canary" diamonds belong to this type, which represents only 10% of known natural diamonds. Synthetic diamond containing nitrogen is Type Ib. Type I diamonds absorb in both the infrared and ultraviolet region, from . They also have a characteristic fluorescence and visible absorption spectrum (see Optical properties of diamond).
Diamond (gemstone)
In some of the more politically unstable central African and west African countries, revolutionary groups have taken control of diamond mines, using proceeds from diamond sales to finance their operations. Diamonds sold through this process are known as "conflict diamonds" or "blood diamonds". 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 Africa and West Africa, the United Nations, the diamond industry and diamond-trading nations introduced the Kimberley Process in 2002, which is aimed at ensuring that conflict diamonds do not become intermixed with the diamonds not controlled by such rebel groups, by providing documentation and certification of diamond exports from producing countries to ensure that the proceeds of sale are not being 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, conflict diamonds smuggled to market continue to persist to some degree (about 2–3% of diamonds traded in 2000 were possible conflict diamonds). Today, according to the Gemological Institute of America, 99% of the worlds' diamonds are conflict-free. According to the 2006 book "The Heartless Stone", two major flaws still hinder the effectiveness of the Kimberley Process: the relative ease of smuggling diamonds across African borders and giving phony histories, and the violent nature of diamond mining in nations that are not in a technical state of war and whose diamonds are therefore considered "clean."
Diamond simulant
Natural minerals that (when cut) optically resemble white diamonds are rare, because the trace impurities usually present in natural minerals tend to impart color. The earliest simulants of diamond were colorless quartz (A form of silica, which also form obsidian, glass and sand), rock crystal (a type of quartz), topaz, and beryl (goshenite); they are all common minerals with above-average hardness (7–8), but all have low RIs and correspondingly low dispersions. Well-formed quartz crystals are sometimes offered as "diamonds", a popular example being the so-called "Herkimer diamonds" mined in Herkimer County, New York. Topaz's SG (3.50–3.57) also falls within the range of diamond.
Diamond simulant
Most "colorless" diamonds are actually tinted yellow or brown to some degree, whereas some artificial simulants are completely colorless—the equivalent of a perfect "D" in diamond color terminology. This "too good to be true" factor is important to consider; colored diamond simulants meant to imitate fancy diamonds are more difficult to spot in this regard, but the simulants' colors rarely approximate. In most diamonds (even colorless ones) a characteristic absorption spectrum can be seen (by a direct-vision spectroscope), consisting of a fine line at 415 nm. The dopants used to impart color in artificial simulants may be detectable as a complex rare-earth absorption spectrum, which is never seen in diamond.
Diamond (gemstone)
The setting diamonds are placed in also affect the performance of light through a diamond. The three most commonly used settings are: Prong, Bezel, and Channel. Prong settings are the most popular setting for diamond jewelry. The prong setting consists of four or six 'claws' that cradle the diamond, allowing the maximum amount of light to enter from all angles, allowing the diamonds to appear larger and more brilliant. In bezel settings the diamond or gemstone is completely surrounded by a rim of metal, which can be molded into any shape to accommodate the stone. Used to set earrings, necklaces, bracelets, and rings, bezel settings can have open or closed backs, and generally can be molded to allow a lot of light to pass through. Channel settings set the stones right next to each other with no metal separating them. This setting is mostly used in wedding and anniversary bands. The outer ridge is then worked over the edges of the stones to create a smooth exterior surface. This also protects the girdle area of the stone.
Diamond cut
Modified brilliants include the "marquise" or "navette" (French for "little boat", because it resembles the hull of a sailboat), "heart", triangular "trillion" (also "trillian" or "trilliant"), "oval", and the "pear" or "drop" cuts. These are the most commonly encountered modified brilliants;
"Oval-shaped diamonds" have been created and introduced by Lazare Kaplan way back in the 1960s. Usually noted to have 56 facets, the weight of such diamonds is estimated by measuring the length and width of the stone. A ratio of 1.33 to 1.66 provides a good traditional range of oval-shaped diamonds.
"Pear-shaped diamonds" are also known as the teardrop shape owing to their resemblance and is considered as a hybrid between the marquise cut and the round brilliant diamond. The stone has one end rounded while the other end is pointed. Pear shape diamonds can opt between varying length and width ratios for the ideal looking pear-shaped diamond. Length to width ratios between 1.45 and 1.75 are most common.
Rough diamond
A rough diamond is a diamond rock which has not been cut or processed. They come in a variety of naturally occurring shapes including octahedrons (eight sided bi-pyramid), cubic and triangular (most commonly macles).
Red diamond
Since red diamonds are classified as diamonds in every sense, they are also graded by the typical four Cs of Connoisseurship: "Color", "Clarity," "Cut" and "Carat weight". Like with all fancy color diamonds, the Color attribute is considered the absolute most important characteristic of the diamond and is largely what determines its value. The next most important attribute is the diamond’s carat weight, followed by its clarity, and cut.
Diamond clarity
The diamond industry uses the term "internal characteristics" instead of "inclusions". For natural diamonds, the "internal characteristics" in the diamond are growth crystals that give the diamond its character and unique fingerprint. When diamonds are graded, they are magnified at 10x power.In 1952, Richard T. Liddicoat, along with Marquis Person, Joe Phillips, Robert Crowningshield and Bert Krashes began to work on a new diamond grading system which they called the "diamond grading and evaluation appraisal". In 1953, they released their new system which assessed three aspects of diamonds; make, color and clarity. They took terminology used in the industry at the time and refined the definitions to produce a clarity scale by which diamonds could be consistently graded. The system at that time contained nine grades: Flawless, VVS, VVS, VS, VS, SI, SI, I, and I. The 'I' of the I, and I grades originally stood for "Imperfect".
Diamond
Synthetic diamonds can be grown from high-purity carbon under high pressures and temperatures or from hydrocarbon gas by chemical vapor deposition (CVD). Imitation diamonds can also be made out of materials such as cubic zirconia and silicon carbide. Natural, synthetic and imitation diamonds are most commonly distinguished using optical techniques or thermal conductivity measurements.
Napoleon Diamond Necklace
While the gems of the Napoleon Diamond Necklace have never been professionally graded by a lapidary (as they have never been removed from their mountings), infrared spectroscopic analysis of the diamonds has shown that they are primarily Type Ia. However, 13 of the 52 largest diamonds in the necklace are of the rare Type IIa variety. A number of the Type Ia diamonds show indications of sulfide crystal imperfections.