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Diamond Cutting
Diamond cutting is the practice of shaping a diamond from a rough stone into a faceted gem. Cutting diamonds requires specialized knowledge, tools, equipment, and techniques because of its extreme difficulty. The first guild of diamond cutters and polishers (Diamantaire) was formed in 1375 in Nuremberg, Germany, and led to the development of various types of "cut". This has two meanings in relation to diamonds. The first is the shape: square, oval, and so on. The second relates to the specific quality of cut within the shape, and the quality and price will vary greatly based on the cut quality. Since diamonds are one of the hardest materials, special diamond-coated surfaces are used to grind the diamond down. The first major development in diamond cutting came with the "Point Cut" during the later half of the 14th century: the Point Cut follows the natural shape of an octahedral rough diamond crystal, eliminating some waste in the cutting process. Diamond cutting, as well as overa ... [...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] |
Mohs Scale Of Mineral Hardness
The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by the German geologist and mineralogist Friedrich Mohs, in his book ''"Versuch einer Elementar-Methode zur naturhistorischen Bestimmung und Erkennung der Fossilien"''; it is one of several definitions of hardness in materials science, some of which are more quantitative. The method of comparing hardness by observing which minerals can scratch others is of great antiquity, having been mentioned by Theophrastus in his treatise ''On Stones'', , followed by Pliny the Elder in his ''Naturalis Historia'', . The Mohs scale is useful for identification of minerals in the field, but is not an accurate predictor of how well materials endure in an industrial setting – ''toughness''. Minerals The Mohs scale of mineral hardness is based on the ability ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brilliant (diamond Cut)
A brilliant is a diamond or other gemstone cut in a particular form with numerous facets so as to have exceptional brilliance. The shape resembles that of a cone and provides maximized light return through the top of the diamond. Even with modern techniques, the cutting and polishing of a diamond crystal always results in a dramatic loss of weight; rarely is it less than 50%. The round brilliant cut is preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. Oddly shaped crystals such as macles are more likely to be cut in a '' fancy cut''—that is, a cut other than the round brilliant—which the particular crystal shape lends itself to. Facet proportions and names The original round brilliant-cut was developed by Marcel Tolkowsky in 1919. The ideal proportions are 100% diameter, 53% table, 43.1% pavilion and 16.2% crown. The girdle and culet (if anynot part of Tolkowsky's original design) are cut from the ideal brilliant. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diamond Cut
A diamond cut is a style or design guide used when shaping a diamond for polishing such as the brilliant cut. Cut does not refer to shape (pear, oval), but the symmetry, proportioning and polish of a diamond. The cut of a diamond greatly affects a diamond's brilliance; this means if it is cut poorly, it will be less luminous. In order to best use a diamond gemstone's material properties, a number of different diamond cuts have been developed. A diamond cut constitutes a more or less symmetrical arrangement of facets, which together modify the shape and appearance of a diamond crystal. Diamond cutters must consider several factors, such as the shape and size of the crystal, when choosing a cut. The practical history of diamond cuts can be traced back to the Middle Ages, while their theoretical basis was not developed until the turn of the 20th century. Design, creation and innovation continue to the present day: new technology—notably laser cutting and computer-aided design— ... [...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
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] |
Cut (gems)
When a gemstone is desired to be used in jewelry, it is cut depending on the size and shape of the rough stone, as well as the desired piece of jewelry to be made. As a general rule, a cut gemstone will reduce the mass (described in the carat) by about 50 percent. There are several techniques available to work with gemstones; among them are sawing, grinding, sanding, lapping, polishing, grilling, and tumbling. The diamond cut planning stage is a complex process that requires the cutter to work with unique rough stones. Very often, the location of the inclusions in a rough stone will determine the type of shape to which a diamond may be cut. For economic reasons, most diamonds are cut to retain weight instead of maximizing brilliance. Types A list of cuts: * Antwerp rose cut *Asscher cut *Baguette cut * Barion cut * Brilliant cut *Briolette *Cabochon * Calla Cut * Ceylon cut *Cushion or old mine cut * Double Dutch rose cut *Emerald cut * Flanders cut *French cut * Heart brill ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Koh-i-Noor
The Koh-i-Noor ( ; from ), also spelled Kohinoor and Koh-i-Nur, is one of the largest cut diamonds in the world, weighing . It is part of the Crown Jewels of the United Kingdom. The diamond is currently set in the Crown of Queen Elizabeth The Queen Mother. There are multiple conflicting legends on the origin of the diamond. However, in the words of Theo Metcalfe there is 'very meager and imperfect' evidence of the early history of the Koh-i-Noor before the 1740s, that can directly tie it to any ancient diamond. There is no record of its original weight, but the earliest attested weight is 186 old carats (191 metric carats or 38.2 g). The first verifiable record of the diamond comes from a history by Muhammad Kazim Marvi of the 1740s Invasion of Northern India. Marvi notes that the Koh-i-Noor as being one of many stones on the Mughal Peacock Throne that Nader Shah looted from Delhi. The diamond then changed hands between various empires in south and west Asia, until being ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diamond Polisher
Diamond is a 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 chemically stable form of carbon at room temperature and pressure, but diamond is metastable and converts to it at a negligible rate under those conditions. Diamond has the highest 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 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 a very ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cleavage (crystal)
Cleavage, in mineralogy and materials science, is the tendency of crystalline materials to split along definite crystallographic structural planes. These planes of relative weakness are a result of the regular locations of atoms and ions in the crystal, which create smooth repeating surfaces that are visible both in the microscope and to the naked eye. If bonds in certain directions are weaker than others, the crystal will tend to split along the weakly bonded planes. These flat breaks are termed "cleavage."Hurlbut, Cornelius S.; Klein, Cornelis, 1985, '' Manual of Mineralogy'', 20th ed., Wiley, The classic example of cleavage is mica, which cleaves in a single direction along the basal pinacoid, making the layers seem like pages in a book. In fact, mineralogists often refer to "books of mica." Diamond and graphite provide examples of cleavage. Both are composed solely of a single element, carbon. But in diamond, each carbon atom is bonded to four others in a tetrahedral pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macle
{{no footnotes, date=April 2009 Macle is a term used in crystallography. It is a crystalline form, twin-crystal or double crystal (such as chiastolite). It is crystallographic twin according to the spinel twin law and is seen in octahedral crystals or minerals such as diamond and spinel. The twin law name comes from the fact that is commonly observed in the mineral spinel. ''Macle'' is an old French word, a heraldic term for a voided lozenge (one diamond shape within another). Etymologically the word is derived from the Latin ''macula'' meaning spot, mesh A mesh is a barrier made of connected strands of metal, fiber, or other flexible or ductile materials. A mesh is similar to a web or a net in that it has many attached or woven strands. Types * A plastic mesh may be extruded, oriented, ex ..., or hole. Bibliography * Georges Friedel (1904) "Étude sur les groupements cristallins", ''Extrait du Bulletin de la Société de l'Industrie minérale'', Quatrième série, T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
