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Diamond Cutting
Diamond cutting is the practice of shaping a Diamond (gemstone), 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 cut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diamond (gemstone)
Diamond is a gemstone formed by diamond cut, cutting a raw diamond. Diamonds have high monetary value as one of the best-known and most sought-after gems, and they have been used as decorative items since ancient times. The hardness of diamond and its high Dispersion (optics), 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 often 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 D ... [...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 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 (English: Attempt at an elementary method for the natural-historical determination and recognition of fossils); 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. Reference minerals The Mohs scale of mineral hardness is based on the ability ... [...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 (diamond cut), brilliant cut. Cut refers to shape (Pear cut, pear, oval), and also the symmetry, proportioning and polish of a diamond. The cut of a diamond greatly affects a diamond's brilliance—a poorly-cut diamond is less luminous. In order to best use a diamond gemstone's material properties of diamond, 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 cutting, 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. The earliest diamond cutting techniques were simply to polish the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Diamonds
Diamond (gemstone), Diamonds occur naturally and vary in size, color, and quality, so the largest of a particular color may not be large in absolute terms, but may still be considered very desirable. Diamonds may also have high valuations in sale prices, and large ones invariably have a noteworthy ownership history. There is no agreed-upon measure of a large or a high-quality diamond, and new ones displace others on any subjective list, so strict inclusion criteria for notable diamonds are not attainable. List of diamonds See also * List of largest rough diamonds * List of Golconda diamonds * List of emeralds by size * List of individual gemstones * List of gold nuggets by size * List of pearls by size * List of sapphires by size References {{DEFAULTSORT:List Of Diamonds Diamond-related lists, Individual diamonds, * Gemstone-related lists, Diamonds ... [...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. Diamond is tasteless, odourless, strong, brittle solid, colourless in pure form, a poor conductor of electricity, and insoluble in water. Another solid form of carbon known as graphite is the Chemical stability, chemically stable form of carbon at Standard 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. 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) can color ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cut (gems)
A gemstone desired to be used in jewelry is cut, carved or made into a bead. The best quality rough is cut, also often referred to as faceting. This is done by a lapidary who decides how to reshape the gemstone using his knowledge of the refractive index of gemstones to maximise any particular crystal's colour or play of light. As a general rule, a cut gemstone will be reduced in mass (in carats) by about 50%. Among the several techniques used to work with gemstones 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. How diamonds have been cut has evolved over time largely to technological advances. Types * Asscher cut * Bagu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Koh-i-Noor
The ; ), also spelled Koh-e-Noor, Kohinoor and Koh-i-Nur, is one of the largest cut diamonds in the world, weighing . It is currently set in the Crown of Queen Elizabeth The Queen Mother. The diamond originated in the Kollur mine in present day Andhra Pradesh, India. According to the colonial administrator Theo Metcalfe, there is "very meagre and imperfect" evidence of the early history of the Koh-i-Noor before the 1740s. 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 by Afsharid Iran under Nader Shah. Marvi notes the Koh-i-Noor as one of many stones on the Mughal Peacock Throne that Nader looted from Delhi. The diamond then changed hands between various empires in south and west Asia, until being given to Queen Victoria after the Second Anglo-Sikh War and the Bri ... [...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. Diamond is tasteless, odourless, strong, brittle solid, colourless in pure form, a poor conductor of electricity, and insoluble in water. 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. 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) can color a diamond blue (boron), yellow (nitrogen), brown (defects), green (radiation exposure), purple, pink, oran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Octahedral
In geometry, an octahedron (: octahedra or octahedrons) is any polyhedron with eight faces. One special case is the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at each vertex. Many types of irregular octahedra also exist, including both convex set, convex and non-convex shapes. Combinatorially equivalent to the regular octahedron The following polyhedra are combinatorially equivalent to the regular octahedron. They all have six vertices, eight triangular faces, and twelve edges that correspond one-for-one with the features of it: * Triangular antiprisms: Two faces are equilateral, lie on parallel planes, and have a common axis of symmetry. The other six triangles are isosceles. The regular octahedron is a special case in which the six lateral triangles are also equilateral. * Tetragonal bipyramids, in which at least one of the equatorial quadrilaterals lies on a plane. The regular octahedron is a special case in which all thr ... [...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. Each is composed solely of a single element, carbon. In diamond, each carbon atom is bonded to four others in a tetrahedral patter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macle
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. A version with five units about a common axis is called a fiveling. ''Macle'' is an old French word, a heraldic term for a voided Lozenge (shape)">lozenge (one diamond Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond is tasteless, odourless, strong, brittle solid, colourless in pure form, a poor conductor of e ... shape within another). Etymologically the word is derived from the Latin ''macula'' meaning spot, mesh, or hole. Bibliography * Georges Friedel (1904) "Étude sur les groupements cristallins", ''Extrait du Bulletin de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
