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Diamond Clarity
Diamond clarity is the quality of diamonds that relates to the existence and visual appearance of internal characteristics 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 are solids, liquids, or gases that were trapped in a mineral as it formed. They may be crystals of a foreign material or even another diamond crystal, or may have produced structural imperfections, such as tiny cracks that make a diamond appear whitish or cloudy. The number, size, color, relative location, orientation, and visibility of inclusions can all affect the relative clarity of a diamond. A clarity grade is assigned based on the overall appearance of the stone under ten times magnification, which is the standard magnification for loupes used in the gem world. Most inclusions present in gem-quality diamonds do not affect the diamonds' performance or structural integrity and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diamond
Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the Chemical stability, chemically stable form of carbon at Standard conditions for temperature and pressure, room temperature and pressure, but diamond is metastable and converts to it at a negligible rate under those conditions. Diamond has the highest Scratch hardness, hardness and thermal conductivity of any natural material, properties that are used in major industrial applications such as cutting and polishing tools. They are also the reason that diamond anvil cells can subject materials to pressures found deep in the Earth. Because the arrangement of atoms in diamond is extremely rigid, few types of impurity can contaminate it (two exceptions are boron and nitrogen). Small numbers of lattice defect, defects or impurities (about one per million of lattice atoms) color diamond blue (bor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diamond (gemstone)
Diamond ''adámas'', meaning "unbreakable", "proper", or "unalterable" is one of the best-known and most sought-after gemstones. They have been used as decorative items since ancient times. The hardness of diamond and its high dispersion of light — giving the diamond its characteristic "fire" — make it useful for industrial applications and desirable as jewelry. Diamonds are such a highly traded commodity that multiple organizations have been created for grading and certifying them based on the "four Cs", which are color, cut, clarity, and carat. Other characteristics, such as presence or lack of fluorescence, also affect the desirability and thus the value of a diamond used for jewelry. 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, which established the fir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Gemological Institute
International Gemological Institute (IGI) is a diamond, colored stone and jewelry certification organization. IGI is headquartered in Antwerp and has offices in New York City, Hong Kong, Mumbai, Bangkok, Tokyo, Dubai, Tel Aviv, Toronto, Los Angeles, Kolkata, New Delhi, Surat, Chennai, Thrissur, Ahmedabad, Shanghai, and Cavalese. Established in 1975, IGI is the largest independent gemological laboratory worldwide. It also runs Schools of Gemology in several locations around the globe. Operations IGI has a staff of over 650 gemologists, appraisers and professional office personnel. The International Gemological Institute "has been at the forefront of technology since its commencement in 1975". This characteristic can be seen in the actions that the IGI has taken recently towards creating an Online Data Retrieval program and its Registration and Recovery Service. The IGI is also perfecting methods to reliably distinguish between synthetic and natural diamonds. IGI provides its se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Diamonds
Diamond (gemstone), Diamonds become famous typically for some combination of their size, color and quality. Diamonds occur naturally in many different colors, so the largest diamond of a particular color may not be large in absolute terms, but it may still be considered very desirable. Diamonds may also have high valuations or sale prices, or go on to have a noteworthy ownership history, but this will tend to occur for diamonds that had some outstanding characteristic to begin with. As new diamonds are discovered, the uniqueness of existing ones may diminish and there is no agreed-upon measure of a large or a high-quality diamond, so a strict inclusion criteria for notable diamonds is not attainable. Diamond A diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. At Standard conditions for temperature and pressure, room temperature and pressure, another solid form of carbon known as graphite is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diamond Color
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 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 when more yellow hue is detectable, while intense pink diamonds or blue diamonds (such as the Hope Diamond) can be dramatically more valuable. Of all colored diamonds, red diamonds are the rarest. The Aurora Pyramid of Hope displays a spectacular array of naturally colored diamonds, including red diamonds. History of color grading Color grading of diamonds was performed as a step of sorting rough diamonds for sale by the London Diamond Syndicate. As the diamond trade developed, early diamond grades were in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blowtorch
A blowtorch, also referred to as a blowlamp, is an ambient air fuel-burning gas lamp used for applying flame and heat to various applications, usually metalworking. Early blowtorches used liquid fuel, carried in a refillable reservoir attached to the lamp. This is distinct from modern gas-fueled torches burning fuel such as a butane torch or a propane torch. Their fuel reservoir is disposable or refillable by exchange. Liquid-fueled torches are pressurized by a piston hand pump, while gas torches are self-pressurized by the fuel evaporation. The term 'blowtorch' is commonly misused as a name for any metalworking torch but properly describes the pressurized liquid fuel torches that predate the common use of pressurized fuel gas cylinders. Torches are available in a vast range of size and output power. The term blowtorch applies to the obsolescent style of smaller liquid fuel torches. Blowtorches are typically a single hand-held unit, with their draught supplied by a natural dra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diamond Enhancement
Diamond enhancements are specific treatments, performed on natural diamonds (usually those already cut and polished into gems), which are designed to improve the visual gemological characteristics of the diamond in one or more ways. These include clarity treatments such as laser drilling to remove black carbon inclusions, fracture filling to make small internal cracks less visible, color irradiation and annealing treatments to make yellow and brown diamonds a vibrant fancy color such as vivid yellow, blue, or pink. The CIBJO and government agencies, such as the United States Federal Trade Commission, explicitly require the disclosure of all 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 diamonds hold a unique or "sacred" place among the gemstones, and should not be treated too radically, if for no other reason than a fear of damaging consum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Market Liquidity
In business, economics or investment, market liquidity is a market's feature whereby an individual or firm can quickly purchase or sell an asset without causing a drastic change in the asset's price. Liquidity involves the trade-off between the price at which an asset can be sold, and how quickly it can be sold. In a liquid market, the trade-off is mild: one can sell quickly without having to accept a significantly lower price. In a relatively illiquid market, an asset must be discounted in order to sell quickly. Money, or cash, is the most liquid asset because it can be exchanged for goods and services instantly at face value. Overview A liquid asset has some or all of the following features: It can be sold rapidly, with minimal loss of value, anytime within market hours. The essential characteristic of a liquid market is that there are always ready and willing buyers and sellers. It is similar to, but distinct from, market depth, which relates to the trade-off between quantit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Gemological Laboratory
European, or Europeans, or Europeneans, may refer to: In general * ''European'', an adjective referring to something of, from, or related to Europe ** Ethnic groups in Europe ** Demographics of Europe ** European cuisine, the cuisines of Europe and other Western countries * ''European'', an adjective referring to something of, from, or related to the European Union ** Citizenship of the European Union ** Demographics of the European Union In publishing * ''The European'' (1953 magazine), a far-right cultural and political magazine published 1953–1959 * ''The European'' (newspaper), a British weekly newspaper published 1990–1998 * ''The European'' (2009 magazine), a German magazine first published in September 2009 *''The European Magazine'', a magazine published in London 1782–1826 *''The New European'', a British weekly pop-up newspaper first published in July 2016 Other uses * * Europeans (band), a British post-punk group, from Bristol See also * * * Europe (disam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Diamond Council
The World Diamond Council is an organization representing the entire diamond value chain including representatives from diamond mining, manufacturing, trading and retail. The council was established in July 2000. The purpose was to create a system to keep the supply chain of diamonds as free as possible from conflict diamonds. In December 2000, the United Nations General Assembly adopted a landmark resolution supporting the creation of an international certification scheme for rough diamonds. By November 2002, negotiations between governments, the international diamond industry and civil society organisations resulted in the creation of the Kimberley Process Certification Scheme (KPCS). The KPCS document sets out the requirements for controlling rough diamond production and trade. The KPCS entered into force in 2003, when participating countries started to implement its rules. The KPCS is credited as being instrumental toward dramatically reducing “conflict diamonds” to less t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aplanatic
In optics, spherical aberration (SA) is a type of aberration found in optical systems that have elements with spherical surfaces. Lenses and curved mirrors are prime examples, because this shape is easier to manufacture. Light rays that strike a spherical surface off-centre are refracted or reflected more or less than those that strike close to the centre. This deviation reduces the quality of images produced by optical systems. Overview A spherical lens has an aplanatic point (i.e., no spherical aberration) only at a radius that equals the radius of the sphere divided by the index of refraction of the lens material. A typical value of refractive index for crown glass is 1.5 (see list), which indicates that only about 43% of the area (67% of diameter) of a spherical lens is useful. It is often considered to be an imperfection of telescopes and other instruments which makes their focusing less than ideal due to the spherical shape of lenses and mirrors. This is an important ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Achromatic Lens
An achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths (typically red and blue) into focus on the same plane. The most common type of achromat is the achromatic doublet, which is composed of two individual lenses made from glasses with different amounts of dispersion. Typically, one element is a negative (concave) element made out of flint glass such as F2, which has relatively high dispersion, and the other is a positive (convex) element made of crown glass such as BK7, which has lower dispersion. The lens elements are mounted next to each other, often cemented together, and shaped so that the chromatic aberration of one is counterbalanced by that of the other. In the most common type (shown), the positive power of the crown lens element is not quite equalled by the negative power of the flint lens element. Together they form a weak positive lens that will b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
