This article addresses treatments designed to enhance the gemological characteristics of diamond. For a broader discussion of diamonds, see A scattering of round-brilliant cut diamonds shows off the many reflecting facets. The mineral diamond is a crystalline form, or allotrope, of carbon (other allotropes of carbon include graphite and coal). Diamonds are renowned for their superlative physical qualities, especially their hardness—the word diamond derives from the... diamond. For other uses of the word diamond, see Diamond has more than one meaning: Diamond is a mineral used in jewelry and tools. Diamonds is a card suit. In geometry, a diamond usually means a rhombus. Diamond Jubilee is a 60th anniversary. The Diamond Sutra is a Buddhist text. Diamond Comic Distributors holds the monopoly on wholesale distribution... diamond (disambiguation).

Diamond enhancements are specific treatments, performed on natural and sometimes Synthetic diamond is diamond produced through chemical or physical processes in a laboratory. Like naturally occurring diamond it is composed of a three-dimensional carbon crystal. Synthetic diamonds are also called cultured diamonds, manufactured diamonds, and artificial diamonds. History Synthetic diamonds were first produced on February 16, 1953 in Stockholm... synthetic A scattering of round-brilliant cut diamonds shows off the many reflecting facets. The mineral diamond is a crystalline form, or allotrope, of carbon (other allotropes of carbon include graphite and coal). Diamonds are renowned for their superlative physical qualities, especially their hardness—the word diamond derives from the... diamonds (usually those already cut and polished into A gemstone is a mineral, rock (as in lapis lazuli) or petrified material that when cut or faceted and polished is collectible or can be used in jewellery. Others are organic, such as amber (fossilised tree resin) and jet (a form of coal). Some beautiful gemstones are too soft or... gems), which are designed to improve the Gemology (gemmology outside the United States) is the science, art and profession of identifying and evaluating gemstones. It may be considered a branch of mineralogy. Some jewelers are gemologists and as such are qualified to identify and appraise gems. There are professional schools and associations of gemologists and certification programs... gemological characteristics — and therefore the value — of the stone in one or more ways. These include Diamond clarity is a quality of diamonds relating to the existence and visual appearance of internal defects of a diamond called inclusions, and surface defects called blemishes. Clarity is one of the four Cs of diamond grading, the others being carat, color, and cut. Inclusions may be crystals of a... clarity treatments such as For alternative meanings see laser (disambiguation). Laser (US Air Force) Operation A laser (light amplification by stimulated emission of radiation) is a device which uses a quantum mechanical effect, stimulated emission, to generate a coherent beam of light from a lasing medium of controlled purity, size, and shape. The output... laser drilling to remove inclusions, application of sealants to fill cracks, Jewelers set diamonds in groups of similar colors. A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. However, in reality almost no gem-sized natural diamonds are absolutely perfect. The color of a diamond may be affected by chemical impurities and/or structural defects... color treatments to improve a white diamond's color grade, and treatments to give fancy color to a white or off-color diamond.

The CIBJO and government agencies such as the The United States of America — also referred to as the United States, the U.S.A., the U.S., America¹, the States, or (archaically) Columbia — is a federal republic of 50 states located primarily in central North America (with the exception of two states: Alaska and Hawaii... United States Categories: United States federal agencies | Stub ... Federal Trade Commission explicitly require the disclosure of most diamond treatments at the time of sale. Some treatments, particularly those applied to clarity, remain highly controversial within the industry — this arises from the traditional notion that diamond holds a unique or "sacred" place among the A gemstone is a mineral, rock (as in lapis lazuli) or petrified material that when cut or faceted and polished is collectible or can be used in jewellery. Others are organic, such as amber (fossilised tree resin) and jet (a form of coal). Some beautiful gemstones are too soft or... gemstones, and should not be treated too radically, if for no other reason than a fear of damaging consumer confidence.

Treated diamonds usually trade at a significant discount to untreated diamonds. This is due to several factors, including relative scarcity — a much larger number of stones can be treated to reach gem quality than are found naturally occurring in a gem quality state — and the potential impermenance of various treatments. Therefore, it is unusual to see a diamond with good overall gemological characteristics undergo treatment. Diamonds which are chosen for treatment are usually those that would be otherwise difficult to sell as gem diamonds, where inclusions or fractures noticeably detract from the beauty of the diamond to even casual observers. In these cases, the loss in value due to treating the diamond is more than overcome by the value added by mitigating obvious flaws.

Clarity enhancements

See also: Diamond clarity is a quality of diamonds relating to the existence and visual appearance of internal defects of a diamond called inclusions, and surface defects called blemishes. Clarity is one of the four Cs of diamond grading, the others being carat, color, and cut. Inclusions may be crystals of a... diamond clarity

The clarity or purity of a diamond — the relative or apparent severity of flaws within the stone — has, like the other "four Cs", a strong bearing on the evaluation of a diamond's worth. The most common flaws or inclusions seen in diamond are fractures (commonly called feathers due to their feathery whitish appearance), and solid foreign This article is about the form of solid matter. For other uses of this word, see Crystal (disambiguation). Insulin crystals A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. Generally, fluid substances... crystals within the diamond; such as The Garnet group of minerals show crystals with a habit of dodecahedrons and trapezohedrons. They are nesosilicates with the same general formula, A3B2(SiO4)3. Many different chemical elements are included in the several varieties of garnet, including calcium, magnesium, aluminium, iron2+, iron3+, chromium, manganese, and titanium. Garnets show no... garnet, Diopside is a monoclinic pyroxene mineral with composition MgCaSi2O6. It forms a solid solution series with hedenbergite (FeCaSi2O6) and augite. Diopside is found in basic igneous rocks as well as in many metamorphic rocks. It is also a constituent of the Earths mantle. Diopside is found in two forms... diopside, or even other diamonds. The size, color, and position of inclusions can reduce the value of a diamond, especially when other gemological characteristics are good. Those who prepare diamonds for sale sometimes choose to reduce the visual impact of inclusions through one or more of a variety of treatments.

Laser drilling

The Combustion or burning is an exothermic reaction between a substance and a gas to release heat. Combustion normally occurs in oxygen (often in the form of gaseous O2) to form oxides, However, combustion can also take place in other gases like chlorine. The products of such reactions usually include water... combustibility of diamond has allowed the development of laser drilling techniques which, on a A microscope (Greek: micron = small and scopos = aim) is an instrument for viewing objects that are too small to be seen by the naked or unaided eye. The science of investigating small objects using such an instrument is called microscopy, and the term microscopic means minute or very small, not... microscopic scale, are able to selectively target and either remove or significantly reduce the visibility of crystal or Iron oxide pigment There are a number of iron oxides: Iron oxides Iron(II) oxide or ferrous oxide (FeO) The black-coloured powder in particular can cause explosions as it readily ignites. Iron(III) oxide or ferric oxide (Fe2O3) known in its natural state as hematite or haematite, but also... iron oxide-stained fracture inclusions. Diamonds have been laser-drilled since at latest the mid- Millennia: 1st millennium - 2nd millennium - 3rd millennium Events and trends Technology Bulletin board system popularity Popularization of personal computers, Walkmans, VHS videocassette recorders, and compact disc (CD) players Introduction of the IBM PC Home video games become enormously popular, most notably Atari until the market crashes in 1983; the rise... 1980s. Laser drilling is often followed by glass infilling.

The drilling process involves the use of an Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. The name means below red (from the Latin infra, below), red being the color of visible light of longest... infrared laser ( The wavelength is the distance between repeating units of a wave pattern. It is commonly designated by the Greek letter lambda (λ). In a sine wave, the wavelength is the distance between peaks: The x axis represents distance, and I would be some varying quantity (for instance air pressure for... wavelength about 1060 nm) to bore very fine holes (less than 0.2 millimeters or 0.005 inches in diameter) into a diamond to create a route of access to an inclusion. Because diamond is transparent to the wavelength of the laser beam, a coating of amorphous General Name, Symbol, Number Carbon, C, 6 Chemical series Nonmetals Group, Period, Block 14 (IVA), 2, p Density, Hardness 2267 kg/m3 0.5 (graphite) 3516 - 3525 kg/m3 10.0 (diamond) Appearance black (graphite) colourless (diamond) Atomic properties Atomic mass 12.0107 u Atomic radius (calc.) 70 (67) pm... carbon or other energy-absorbent substance is applied to the surface of the diamond to initiate the drilling process. The laser then burns a narrow tube to the inclusion. Once the included crystal has been reached by the drill, the diamond is immersed in Sulfuric acid (British English: sulphuric acid), H2SO4, is a strong mineral acid. It is soluble in water at all concentrations. The old name for sulfuric acid was oil of vitriol. When high concentrations of SO3(g) are added to sulfuric acid, H2S2O7 forms. This is called fuming sulfuric acid or... sulfuric acid to dissolve the crystal or iron oxide staining. This process is not effective for inclusions which are diamonds themselves, as diamond is not A solvent is a liquid that dissolves a solid, liquid, or gaseous solute, resulting in a solution. The most common solvent in everyday life is water. The term organic solvent refers to most other solvents that are organic compounds and contain carbon atoms. Solvents usually have a low boiling point... soluble in sulfuric acid.

Several inclusions can be thusly removed from the same diamond, and under microscopic inspection the fine bore holes are readily detectable. They are whitish and more or less straight, but may change direction slightly, and are often described as having a "wrinkled" appearance. In reflected light, the surface-reaching holes can be seen as dark circles breaching the diamond's facets. The diamond material removed during the drilling process is destroyed, and is often replaced with glass infilling, using the fracture filling techniques described below.

Fracture filling

Around the same time as the laser drilling technique was developed, research began on the fracture filling of diamonds to better conceal their flaws. The glass filling of diamond often follows the laser drilling and acid-etching of inclusions, though if the fractures are surface-reaching, no drilling may be required. This process, which involves the use of specially-formulated For eyeglasses, see spectacles. For the drinking vessel, see glass (drinkware). The physics definition of a glass is a uniform amorphous solid material, usually produced when a suitably viscous molten material cools very rapidly, thereby not giving enough time for a regular crystal lattice to form. A simple example is... glasses with a The refractive index of a material is the factor by which electromagnetic radiation is slowed down (relative to vacuum) when it travels inside the material. For a non-magnetic material, the square of the refractive index is the materials dielectric constant (sometimes expressed as the relative permittivity multiplied by... refractive index approximating that of diamond, was pioneered by Zvi Yehuda of Ramat Gan (רמת-גן) is a city in Israel, on the central coastal strip, just east of Tel Aviv, and part of the metropolis known as Gush Dan, in the Tel Aviv District. It has about 150,000 residents. Ramat Gan began as an agricultural settlement in... Ramat Gan, The State of Israel (Hebrew: מדינת ישראל, translit.: Medinat Yisrael; Arabic: دولة اسرائيل, translit.: Daulat Israil) is a country in the Middle East on the eastern edge of the Mediterranean Sea... Israel. Yehuda is now a brand name applied to diamonds treated in this manner, and the process has apparently changed little since its inception. Koss & Schechter, another Israel-based firm, attempted to modify Yehuda's process in the Events and trends Technology Explosive growth of the Internet; decrease in the cost of computers and other technology Reduction in size and cost of mobile phones leads to a massive surge in their popularity Year 2000 problem (commonly known as Y2K) Microsoft Windows operating system becomes virtually ubiquitous on IBM... 1990s by using The halogens are a chemical series. They are the elements in Group 17 (old-style: VII or VIIA) of the periodic table: fluorine, chlorine, bromine, iodine, and astatine. The word comes from Greek roots meaning salt and creator. These elements are diatomic molecules in their natural form. They require one... halogen-based glasses, but this was unsuccessful. The details behind the Yehuda process have been kept secret, but the filler used is reported to be lead oxychloride glass, which has a fairly low The melting point of a solid is the temperature at which it changes state from solid to liquid. When considered as the temperature of the reverse change, it is referred to as the freezing point. For example, the melting point of the element mercury is 234.32 kelvins (−38... melting point. The State nickname: Empire State Other U.S. States Capital Albany Largest city New York Governor George Pataki Official languages None Area 141,205 km² (27th)  - Land 122,409 km²  - Water 18,795 km² (13.3%) Population ( 2000)  - Population 18,976,457 (3rd... New York-based Dialase also treats diamonds via a Yehuda-based process, which is believed to use lead- General Name, Symbol, Number Bismuth, Bi, 83 Chemical series Poor metals Group, Period, Block 15 (VA), 6, p Density, Hardness 9.78 g/cm3, 2.25 Appearance lustrous reddish white Atomic properties Atomic weight 208.98038 g/mol Atomic radius (calc.) 160 (143) pm Covalent radius 146 pm van der... bismuth oxychloride glass.

The glass present in fracture-filled diamonds can usually be detected by a trained gemologist under the microscope: the most obvious signs — apart from the surface-reaching bore holes and fractures associated with drilled diamonds — are air bubbles and flow lines within the glass, which are features never seen in untreated diamond. More dramatic is the so-called "flash effect", which refers to the bright flashes of color seen when a fracture-filled diamond is rotated; the color of these flashes ranges from an electric blue or purple to an orange or yellow, depending on lighting conditions (light field and dark field, respectively). The flashes are best seen with the field of view nearly parallel to the filled fracture's plane. In strongly colored diamonds the flash effect may be missed if examination is less than thorough, as the stone's body color will conceal one or more of the flash colors. For example, in brown-tinted "champagne" diamonds, the orange-yellow flashes are concealed, leaving only the blue-purple flashes to be seen. One last but important feature of fracture-filled diamonds is the color of the glass itself: it is often a yellowish to brownish, and along with being highly visible in transmitted light, it can significantly impact the overall color of the diamond. Indeed, it is not unusual for a diamond to fall an entire color grade after fracture-filling. For this reason fracture-filling is normally only applied to stones whose size is large enough to justify the treatment: however, stones as small as 0.02 For Carat as a unit of purity see Carat (purity) The carat is a unit of mass used for gems. The word derives from the Greek keration (fruit of the carob), via Arabic and Italian. In the past, different countries each had their own carat, roughly equivalent to a carob... carats have been fracture-filled. Therefore any diamond with surface-reaching fractures is immediately suspected of glass filling.

The fracture-filling of diamond is a controversial treatment within the industry — and increasingly among the public as well — due to its radical and impermanent nature. The filling glass melts at such a low temperature that it easily "sweats" out of a diamond under the heat of a jeweler's torch; thus routine jewelry repair can lead to a complete degradation of clarity or in some cases shattering, especially if the jeweler is not aware of the treatment. Similarly, a fracture-filled diamond placed in an Ultrasound is sound with a frequency greater than the upper limit of human hearing, approximately 20 kilohertz. Some animals, such as dogs, dolphins, and bats, have an upper limit that is greater than that of the human ear and thus can hear ultrasound. Ultrasound has industrial and medical applications. Medical... ultrasonic cleaner may not survive intact. Yehuda diamonds are however given a warranty, which allows owners of their diamonds to return them for retreatment following any degradation of the glass filling.

It is notable that most major gemological laboratories, including that of the influential Gemological Institute of America, refuse to issue certificates for fracture-filled diamonds. Labs that do certify these diamonds may render any treatment benefit moot by disregarding apparent clarity and instead assigning the diamond a grade reflecting its original, pre-treatment clarity.

Color enhancements

See also: Jewelers set diamonds in groups of similar colors. A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. However, in reality almost no gem-sized natural diamonds are absolutely perfect. The color of a diamond may be affected by chemical impurities and/or structural defects... diamond color

The color of a diamond can be artificially altered by three distinct methods: Irradiation is the process whereby an item is exposed to radiation. In common usage the term refers specifically to ionizing radiation, and to a level of radiation that will be destructive to life, rather than simply exposure to normal levels of radiation, or background radiation. Some forms of radiation will... irradiation with high-energy Helium atom (not to scale) Showing two protons (red), two neutrons (green) and a probability cloud (gray) of two electrons (yellow). In physics, a subatomic particle is a particle smaller than an atom. These include atomic constituents such as electrons, protons, and neutrons (protons and neutrons are actually composite particles... subatomic particles; the application of thin films or coatings; and the combined application of high Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. General description The formal properties of temperature are studied in thermodynamics. Formally, temperature is that property which governs the transfer of thermal... temperature and high Pressure (symbol: p or P) is the measure of the force that acts on a unit area. where: p is the pressure F is the force A is the area Often F is taken to be the of the magnitude of the mean vector force normal to the surface of... pressure (HTHP). The first two methods can only modify color, usually to turn an off-color Cape series stone (see This article addresses the material properties of diamond. For a broader discussion of diamonds, see diamond. For other uses of the word diamond, see diamond (disambiguation). Diamond is transparent to opaque, optically isotropic crystalline carbon. It is the hardest naturally-occurring material known—owing to its strong covalent bonding... Material properties of diamond: Composition and color) into a more desirable fancy-colored stone. Because some irradiation methods produce only a thin "skin" of color, they are applied to diamonds that are already cut and polished. Conversely, HTHP is used to modify and remove color from either rough or cut diamonds—but only certain diamonds are treatable in this manner. Irradiation and HTHP treatments are usually permanent insofar as they will not be reversed under normal conditions of jewelry use, whereas thin films are impermanent. The CIBJO requires all color enhancements of diamond to be disclosed.

Irradiation

Sir Categories: People stubs | 1832 births | 1919 deaths | British scientists | English chemists | Physicists | Discoverer of a chemical element ... William Crookes, a gem connoisseur as well as a A chemist is a scientist who specializes in chemistry. The word derives from the older term alchemist. Also, in British English, the term is used for a pharmacist or a pharmacists shop. See also: List of chemists, Nobel Prize in Chemistry, Biography. Categories: Chemistry | Science occupations ... chemist and The word physicist should not be confused with physician, which means medical doctor. A physicist is a scientist trained in physics. Physicists are employed by universities as professors, lecturers, researchers, and by laboratories in industry. Employment as a professional physicist generally requires a doctoral degree. However, many people who have... physicist, was the first to discover radiation's effects on diamond color when in 1904 is a leap year starting on a Friday (link will take you to calendar). Events January-March January 7 - The distress signal CQD is established only to be replaced two years later by SOS. February 7 - The Great Baltimore Fire in Baltimore, Maryland destroys over 1,500 buildings in... 1904 he conducted a series of experiments using General Name, Symbol, Number Radium, Ra, 88 Series Alkali earth metals Group, Period, Block 2(IIA), 7, s Density, Hardness 5000 kg/m3, no data Appearance Silvery white metallic Atomic Properties Atomic weight (226.0254) amu Atomic radius 215 pm Covalent radius no data van der Waals radius no data... radium salts. Diamonds enveloped in radium salt slowly turned a dark green; this color was found to be localized in blotchy patches, and it did not penetrate past the surface of the stone. The emission of An alpha particle is deflected by a magnetic field Alpha particles or alpha rays are a form of particle radiation which are highly ionizing and have low penetration. They consist of two protons and two neutrons bound together into a particle that is identical to a helium nucleus, and can... alpha particles by the radium was responsible. Unfortunately radium treatment also left the diamond strongly Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. Decay is said to occur in the parent nucleus and produce a daughter nucleus. The trefoil symbol is used to indicate radioactive material. The Unicode encoding of this symbol is U+2622 (☢... radioactive, to the point of being unwearable. A diamond octahedron so treated was donated by Crookes to the The main entrance to the British Museum The British Museum is one of the worlds greatest and most famous museums. It was established in 1753 by Sir Hans Sloane, a physician and scientist who collected a great deal of literature and art at its present site at Montague House... British Museum in 1914 is a common year starting on Thursday. (see link for calendar) Events January 4 - 77 seal hunters freeze to death on ice near Labrador. January 5 - Ford Motor Company announces an eight-hour workday and a minimum wage of $5 for a days labor. February 13 - Copyright: In... 1914, where it remains today: it has not lost its color nor its radioactivity.

Nowadays diamond is safely irradiated in four ways: For alternative meanings see proton (disambiguation). Properties In physics, the proton (Greek proton = first) is a subatomic particle with a positive fundamental electric charge of 1.6 × 10−19 coulomb and a mass of 938 MeV/c2 (1.6726231 × 10−27 kg, or about 1800 times the mass... proton (alpha particle) and Deuterium (symbol 2H) is a stable isotope of hydrogen with a natural abundance of one atom in 6500 of hydrogen. The nucleus of deuterium (called a deuteron) has one proton and one neutron, whereas a normal hydrogen nucleus just has one proton. Deuterium is also called heavy hydrogen. While it... deuteron bombardment via A large cyclotron magnet. Click on the image for additional information about this mechanism A cyclotron is a machine designed to accelerate beams of charged particles by using a high frequency alternating voltage across a magnetic field to spiral the beam out and eventually deflect it once the beams... cyclotrons; This article is about electromagnetic radiation. For the power metal band, see Gamma Ray (band) Gamma rays (often denoted by the Greek letter gamma, γ) are an energetic form of electromagnetic radiation (see Electromagnetic spectrum) produced by radioactivity or other nuclear or subatomic processes such as electron-positron annihilation. Gamma... gamma ray bombardment via exposure to General Name, Symbol, Number cobalt, Co, 27 Chemical series transition metals Group, Period, Block 9 , 4, d Density, Hardness 8.9 Mg/m3, 5.0 Appearance metallic with grey tinge Atomic properties Atomic weight 58.933200 amu Atomic radius (calc.) 135 (152) pm Covalent radius 126 pm van der Waals... cobalt-60; Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 940 MeV/c² (1.6749 × 10-27 kg, slightly more than a proton). Its spin is ½. The nucleus of most atoms (all except the most common isotope of Hydrogen, which consists of... neutron bombardment via the piles of Nuclear power station at Leibstadt, Switzerland. The nuclear reactor is inside the dome-shaped containment building. A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate (as opposed to a nuclear explosion, where the chain reaction occurs in a split... nuclear reactors; and Properties The electron (also called negatron, commonly represented as e−) is a subatomic particle. In an atom the electrons surround the nucleus of protons and neutrons in an electron configuration. The word electron is a transliteration of the Greek word ηλεκτρον, which... electron bombardment via A Van de Graaff generator For the band with a similar name, see Van der Graaf Generator. A Van de Graaff generator is a machine which uses a moving belt to accumulate very high charges on a hollow metal globe. The potential differences achieved in modern Van de Graaff generators... Van de Graaff generators. These high-energy particles physically alter the diamond's In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. A crystal structure is composed of a unit cell, a set of atoms arranged in a particular way, which is periodically repeated in three dimensions on a lattice. The spacings between unit cells in... crystal lattice, knocking carbon atoms out of place and producing color centers. Irradiated diamonds are all some shade of green, black, or blue after treatment, but most are The word anneal has several meanings: In metallurgy and materials science annealing is a heat treatment wherein the microstructure of a material is altered, causing changes in its properties such as strength and hardness. Typically, this results in softening of the metal through removal of crystal defects and the internal... annealed to further modify their color into bright shades of yellow, orange, brown, or pink. The annealing process increases the mobility of individual carbon atoms, allowing some of the lattice defects created during irradiation to be corrected. The final color is dependent on the diamond's composition and the temperature and length of annealing.

Cyclotroned diamonds have a green to blue-green color confined to the surface layer: they are later annealed to 800°C to produce a yellow or orange color. They remain radioactive for only a few hours after treatment, and due to the directional nature of the treatment and the cut of the stones, the color is imparted in discrete zones. If the stone was cyclotroned through the pavilion (back), a characteristic "umbrella" of darker color will be seen through the crown (top) of the stone. If the stone was cyclotroned through the crown, a dark ring is seen around the girdle (rim). Stones treated from the side will have one half colored deeper than the other. Cyclotron treatment is now uncommon.

Gamma ray treatment is also uncommon, because although it is the safest and cheapest irradiation method, successful treatment can take several months. The color produced is a blue to blue-green which penetrates the whole stone. Such diamonds are not annealed. The blue color can sometimes approach that of natural Type IIb diamonds, but the two are distinguished by the latter's A semiconductor is a material that is an insulator at very low temperature, but which has a sizable electrical conductivity at room temperature. The distinction between a semiconductor and an insulator is not very well-defined, but roughly, a semiconductor is an insulator with a band gap small enough that... semiconductive properties. As with most irradiated diamonds, most gamma ray-treated diamonds were originally tinted yellow; the blue is usually modified by this tint, resulting in a perceptible greenish cast.

The two most common irradiation methods are neutron and electron bombardment. The former treatment produces a green to black color that penetrates the whole stone, while the latter treatment produces a blue, blue-green, or green color that only penetrates about 1 millimeter deep. Annealing of these stones (from 500–900°C for neutron-bombarded stones and from 500–1200°C for electron-bombarded stones) produces orange, yellow, brown, or pink. Blue to blue-green stones that are not annealed are separated from natural stones in the same manner as gamma ray-treated stones.

Prior to annealing, nearly all irradiated diamonds possess a characteristic An absorption spectrum is a diagram depicting the wavelengths of electromagnetic radiation absorbed by a material, usually a gas. It can be regarded as the opposite to an emission spectrum, which is a depiction of the specific wavelengths emitted by a material. Let us consider white light, which consists of... absorption spectrum consisting of a fine line in the far red, at 741 nm — this is known as the GR1 line and is usually considered a strong indication of treatment. Subsequent annealing usually destroys this line, but creates several new ones; the most persistent of these is at 595 nm. If however an irradiated diamond is annealed above 1000°C, the 595 line too is destroyed, but leaves two new lines at 1936 and 2024 nm in the infrared. These lines are detected in gemological laboratories using In physics, spectrophotometry is the quantitative study of spectra. It is more specific than the general term electromagnetic spectroscopy in that spectrophotometry deals with visible light, near-ultraviolet, and near-infrared. Also, the term does not cover time-resolved spectroscopic techniques. Spectrophotometry involves the use of a spectrophotometer. A spectrophotometer... spectrophotometers: the lines are best detected when the stone is cooled to very low temperatures (below -150°C).

It should be noted that some irradiated diamonds are completely natural. One famous example is the The Dresden Green diamond is a 41 carat natural green diamond, which has a historical record dating to 1722, when a London news-sheet carried an article about it in its Oct 25-27th edition. It is named after the capital of Saxony, Germany where it has been on display... Dresden Green Diamond. In these natural stones the color is imparted by "radiation burns" in the form of small patches, usually only skin deep, as is the case in radium-treated diamonds. Naturally irradiated diamonds also possess the GR1 line.

Coatings

The application of colored Tin foil or tinfoil is a thin leaf made of tin. Commonly, it is a misnomer for aluminium foil, as tin foil was commercially available before the aluminium counterpart, and some people continue to refer to the new product by the name of the old one. Tin foil is stiffer... tinfoil to the pavilion (back) surfaces of gemstones was common practice during the The Georgian era is a period of British history, normally defined as including the reigns of the kings George I, George II, George III and George IV, i.e. covering the period from 1714 to 1830. Sometimes the reign of William IV (1830 to 1837) is also included. The expression... Georgian and Queen Victoria (shown here on the morning of her Accession to the Throne, June 20, 1837) gave her name to the historic era. The Victorian Era of Great Britain is considered the height of the British industrial revolution and the apex of the British Empire. It is often defined as... Victorian era; this was the first treatment — aside from cutting and polishing — applied to diamond. Foiled diamonds are mounted in closed-back jewelry settings, which may make their detection problematic. Under magnification, areas where the foil has flaked or lifted away are often seen; moisture that has entered between the stone and foil will also cause degradation and uneven color. Because of its Antique can stand for any of several things: An antique is an object, often furniture or any other domestic item, that is highly valued because of its age, or because it belongs to a specific time period. Antique is a province of the Philippines. Antique is a musical duo from... antique status, the presence of foiled diamonds in older jewelry will not detract from its value.

In modern times, more sophisticated surface coatings have been developed: these include violet-blue dyes and vacuum-sputtered films resembling the Magnesium fluoride (MgF2) is a white crystalline salt composed of one magnesium ion and two fluoride ions. solubility in water: 0.076 g/l at 18°C density: 3.148 g/cm³ melting point: 1263°C boiling point: 2227°C Refractive index: 1.38 at 550nm It is used in... magnesium fluoride coating on A camera is a device used to take images (usually photographs), either singly or in sequence, with or without sound, such as with video cameras. The name is derived from camera obscura, Latin for dark chamber, an early mechanism for projecting images in which an entire room functioned much as... camera lenses. These coatings effectively whiten the apparent color of a yellow-tinted diamond, because the two colors are Two colors are called complementary if, when mixed in an additive system, they produce a shade of gray. In a subtractive system, two complementary colors mix to produce the color of the illuminant. Examples of complementary pairs are: red and cyan green and magenta blue and yellow Complementary colors in... complementary and act to cancel each other out. Usually only applied to the pavilion or girdle region of a diamond, these coatings are among the hardest treatments to detect — while the dyes may be removed in hot water or In general usage, alcohol (from Arabic al-khwl الكحول, or al-ghawl الغول) refers almost always to ethanol, also known as grain alcohol, and often to any beverage that contains ethanol (see alcoholic beverage). This sense underlies the term alcoholism ( addiction... alcohol with ease, the vacuum-sputtered films require a dip in sulfuric acid to remove. The films can be detected under high magnification by the presence of raised areas where air bubbles are trapped, and by worn areas where the coating has been scratched off. These treatments are considered In the broadest sense a fraud is any crime (or civil wrong) for gain that utilises some deception practiced on the victim as its principal method. In law, fraud is the crime or offense of deliberately deceiving another in order to damage them -- usually, to obtain property or services from... fraudulent unless disclosed.

Another coating treatment applies a thin film of Synthetic diamond is diamond produced through chemical or physical processes in a laboratory. Like naturally occurring diamond it is composed of a three-dimensional carbon crystal. Synthetic diamonds are also called cultured diamonds, manufactured diamonds, and artificial diamonds. History Synthetic diamonds were first produced on February 16, 1953 in Stockholm... synthetic diamond to the surface of a diamond simulant. This gives the simulated diamond certain characteristics of real diamond, including higher resistance to wear and scratching, higher thermal conductivity, and lower electrical conductivity. While resistance to wear is a legitimate goal of this technique, some employ it in order to make diamond simulants more difficult to detect through conventional means, which may be fraudulent if they are attempting to represent a simulated diamond as real.

High-temperature, high-pressure

A small number of otherwise gem-quality stones that possess a brown body color can have their color significantly lightened or altogether removed by HTHP treatment, which was introduced by The General Electric Company, or GE, (NYSE: GE) is a multinational technology and services company. As of 2005 it was the worlds largest corporation in terms of market cap ([1]). It should not be confused with The General Electric Company plc, which was renamed Marconi plc in 1999. In... General Electric in 1999 is a common year starting on Friday of the Common Era, and was designated the International Year of Older Persons by the United Nations. Events Kosovo War Shooting in Littleton, Colorado, United States, leaves several high school students dead. Y2K preparation was a major event in 1999 both in... 1999. Diamonds treated this way are all Type IIa and owe their marring color to structural defects that arose during This article is about the form of solid matter. For other uses of this word, see Crystal (disambiguation). Insulin crystals A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. Generally, fluid substances... crystal growth, known as plastic deformations, rather than to interstitial General Name, Symbol, Number Nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15 (VA), 2 , p Density 1.2506 kg/m3 Hardness NA Appearance colorless Atomic properties Atomic weight 14.0067 amu Atomic radius (calc.) 65 (56) pm Covalent radius 75 pm van der Waals radius 155 pm Electron... nitrogen impurities as is the case in most diamonds with brown color. HTHP treatment is believed to repair these deformations, and thus whiten the stone. Type Ia diamonds, which have nitrogen impurities present in clusters that do not normally affect body color, can also have their color altered by HTHP. This is done primarily by the company Nova Diamond and results in a vivid fancy yellow or green, without the need for irradiation. Some synthetic diamonds have also been given HTHP treatment to alter their optical properties and thus make them harder to differentiate from natural diamonds. Pressure (symbol: p or P) is the measure of the force that acts on a unit area. where: p is the pressure F is the force A is the area Often F is taken to be the of the magnitude of the mean vector force normal to the surface of... Pressures of up to 70,000 When expressed as a measurement, an atmosphere or standard atmosphere is a unit of pressure roughly equal to the average atmospheric pressure at sea level on the earth. It is defined as the pressure under 760 mm of mercury. 1 atm = 101325 Pa = 101325 kg/m·s² = 101325 N/m... atmospheres and Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. General description The formal properties of temperature are studied in thermodynamics. Formally, temperature is that property which governs the transfer of thermal... temperatures of up to 2,000°C are used in HTHP.

Definitive identification of HTHP stones is left to well-equipped gemological laboratories, where FTIR of a thin film of ethanol in the liquid phase. Fourier transform spectroscopy is a measurement technique whereby spectra are collected based on the response from a pulse of electromagnetic radiation. It can be applied to variety of types of spectroscopy including infrared spectroscopy (FTIR), nuclear magnetic resonance, and... Fourier transform spectroscopy (FTIR) and Raman spectroscopy is a spectroscopic technique used in condensed matter physics and chemistry to study vibrational, rotational, and other low-frequency modes in a system. It relies on inelastic scattering, or Raman scattering of monochromatic light, usually from a laser in the visible, near infrared, or near ultraviolet range. Phonons... Raman spectroscopy are used to analyze the visible and infrared absorption of suspect diamonds to detect characteristic absorption lines, such as those indicative of exposure to high temperatures. Indicative features seen under the microscope include: internal graining (Type IIa); partially healed feathers; a hazy appearance; black cracks surrounding inclusions; and a beaded or frosted girdle. Diamonds treated to remove their color by General Electric are given laser inscriptions on their girdles: these inscriptions read "GE POL", with "POL" standing for Pegasus Overseas Ltd, a partnered firm. It is possible to polish this inscription away, so its absence cannot be a trusted sign of natural color. Although it is permanent, HTHP treatment should be disclosed to the buyer at the time of sale.

See also

• This article addresses the material properties of diamond. For a broader discussion of diamonds, see diamond. For other uses of the word diamond, see diamond (disambiguation). Diamond is transparent to opaque, optically isotropic crystalline carbon. It is the hardest naturally-occurring material known—owing to its strong covalent bonding... Material properties of diamond
• Synthetic diamond is diamond produced through chemical or physical processes in a laboratory. Like naturally occurring diamond it is composed of a three-dimensional carbon crystal. Synthetic diamonds are also called cultured diamonds, manufactured diamonds, and artificial diamonds. History Synthetic diamonds were first produced on February 16, 1953 in Stockholm... Synthetic diamond
• Diamond simulants
• Jewelers set diamonds in groups of similar colors. A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. However, in reality almost no gem-sized natural diamonds are absolutely perfect. The color of a diamond may be affected by chemical impurities and/or structural defects... Diamond color
• Diamond clarity is a quality of diamonds relating to the existence and visual appearance of internal defects of a diamond called inclusions, and surface defects called blemishes. Clarity is one of the four Cs of diamond grading, the others being carat, color, and cut. Inclusions may be crystals of a... Diamond clarity
• This article addresses the many styles of diamond cut. For a broader discussion of diamonds, see diamond. For other uses of the word diamond, see diamond (disambiguation). In order to best utilize a diamond gemstones superlative material properties, a number of different diamond cuts have been developed. A diamond... Diamond cut

External links

• Adamas Gemological Laboratory (http://www.gis.net/~adamas) makes spectrophotometer machines that measure the color of gems. The machines can be programmed to distinguish natural, artificial, and color-enhanced gems.

References

• O'Donoghue, Michael, and Joyner, Louise (2003). Identification of gemstones, pp. 28–35. Butterworth-Heinemann, Great Britain. ISBN 0750655127
• Read, Peter G. (1999). Gemmology (2nd ed.), pp. 167–170. Butterworth-Heinemann, Great Britain. ISBN 0750644117
• Webster, Robert, and Read, Peter G. (Ed.) (2000). Gems: Their sources, descriptions and identification (5th ed.), pp. 683–684, 692–696. Butterworth-Heinemann, Great Britain. ISBN 0750616741