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Gemmology
Gemology or gemmology is the science dealing with natural and artificial gemstone materials. It is a geoscience and a branch of mineralogy. Some jewelers (and many non-jewelers) are academically trained gemologists and are qualified to identify and evaluate gems. History Rudimentary education in gemology for jewellers and gemologists began in the nineteenth century, but the first qualifications were instigated after the National Association of Goldsmiths of Great Britain (NAG) set up a Gemmological Committee for this purpose in 1908. This committee matured into the Gemmological Association of Great Britain (also known as Gem-A), now an educational charity and accredited awarding body with its courses taught worldwide. The first US graduate of Gem-A's diploma course, in 1929, was Robert Shipley, who later established both the Gemological Institute of America and the American Gem Society. There are now several professional schools and associations of gemologists and certificatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gemmological Association Of Great Britain
The Gemmological Association of Great Britain (Gem-A) is an international gemmology education and qualifications body based in the United Kingdom. History Gem-A dates back to 1908 when a gemmological committee was established by ''The National Association of Goldsmiths''. The aim of the committee was how to best provide the United Kingdom jewellery trade with recognised gemmology qualifications. The recent development of synthetic rubies, synthetic sapphires and cultured pearls had made formal education essential. This committee matured into the Gemmological Association of Great Britain, a Branch of the NAG, and eventually became a wholly independent organisation. Now Gem-A is a registered United Kingdom-based charity and its gemmology and diamond courses are taught in some 25 countries worldwide. Coat of Arms One of the most common symbols used to denote the Association, the Coat of Arms is based upon a design submitted by H. Ellis Tomlinson on behalf of the Association i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gemstone
A gemstone (also called a fine gem, jewel, precious stone, or semiprecious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks (such as lapis lazuli, opal, and obsidian) and occasionally organic materials that are not minerals (such as amber, jet, and pearl) are also used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other physical properties that have aesthetic value. Rarity and notoriety are other characteristics that lend value to gemstones. Apart from jewelry, from earliest antiquity engraved gems and hardstone carvings, such as cups, were major luxury art forms. A gem expert is a gemologist, a gem maker is called a lapidarist or gemcutter; a diamond cutter is called a diamantaire. Characteristics and classification The traditional classification in the West, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peridot (Mg, Fe)2SiO4 In The Rough Form And A Cut And Polished Gem - Sara Abey
Peridot ( /ˈpɛr.ɪˌdɒt, -ˌdoʊ/ ''PERR-ih-dot, -doh''), sometimes called chrysolite, is a deep yellowish-green transparent variety of olivine. Peridot is one of the few gemstones that only occurs in one color. Peridot can be found in mafic and ultramafic rocks occurring in lava and peridotite xenoliths of the mantle. The gem occurs in silica-deficient rocks such as volcanic basalt and pallasitic meteorites. Peridot is one of only two gems observed to be formed not in the Earth’s crust, but in the molten rock of the upper mantle. Gem-quality peridot is rare on Earth's surface due to its susceptibility to weathering during its movement from deep within the mantle to the surface. Peridot has the formula of (Mg, Fe)2SiO4. Peridot is one of the birthstones for the month of August. Etymology The origin of the name ''peridot'' is uncertain. The '' Oxford English Dictionary'' suggests an alteration of Anglo– Norman (classical Latin -), a kind of opal, rather tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ruby
A ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum ( aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called sapphires. Ruby is one of the traditional cardinal gems, alongside amethyst, sapphire, emerald, and diamond. The word ''ruby'' comes from ''ruber'', Latin for red. The color of a ruby is due to the element chromium. Some gemstones that are popularly or historically called rubies, such as the Black Prince's Ruby in the British Imperial State Crown, are actually spinels. These were once known as "Balas rubies". The quality of a ruby is determined by its color, cut, and clarity, which, along with carat weight, affect its value. The brightest and most valuable shade of red, called blood-red or pigeon blood, commands a large premium over other rubies of similar quality. After color follows clarity: similar to diamonds, a clear stone will com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loupe
A loupe ( ) is a simple, small magnification device used to see small details more closely. They generally have higher magnification than a magnifying glass, and are designed to be held or worn close to the eye. A loupe does not have an attached handle, and its focusing lens(es) are contained in an opaque cylinder or cone. On some loupes this cylinder folds into an enclosing housing that protects the lenses when not in use. Optics Three basic types of loupes exist: * Simple lenses, generally used for low-magnification designs because of high optical aberration. * Compound lenses, generally used for higher magnifications to control optical aberration. * Prismatic, multiple lenses with prisms. Uses Loupes are used in many professions where magnification enables precision work to be done with greater efficiency and ease. Examples include surgery, dentistry, ophthalmology, the jewelry trade, gemology, and watchmaking. Loupes are also sometimes used in photography and printing. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dichroscope
A dichroscope is a pocket instrument used in the field of gemology, and can be used to test transparent gemstones (crystals). Experienced gemologists, observing the pleochroism of some gems, can successfully detect gemstones from other artificial stones using this instrument. There are two types of dichroscopes available: calcite and polarizing. Of the two, calcite gives better results and is widely used by experienced gemologists. With the polarizing type, only one pleochroic color can be seen at a time. This makes the process time-consuming and difficult, though it is the most economical way to get results. The dichroscope has been used since at least the start of the nineteenth century. Calcite Dichroscope A calcite dichroscope shows a gem's pleochroic colors in contrast with one another, allowing the viewer to easily determine whether the stone is singly or doubly refractive (uniaxial or biaxial, respectively). Singly refractive stones do not split light that enters them, l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glass
Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenching) of the molten form; some glasses such as volcanic glass are naturally occurring. The most familiar, and historically the oldest, types of manufactured glass are "silicate glasses" based on the chemical compound silica (silicon dioxide, or quartz), the primary constituent of sand. Soda–lime glass, containing around 70% silica, accounts for around 90% of manufactured glass. The term ''glass'', in popular usage, is often used to refer only to this type of material, although silica-free glasses often have desirable properties for applications in modern communications technology. Some objects, such as drinking glasses and eyeglasses, are so commonly made of silicate-based glass that they are simply called by the name of the material. Despite bei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cubic Zirconia
Cubic zirconia (CZ) is the cubic crystalline form of zirconium dioxide (ZrO2). The synthesized material is hard and usually colorless, but may be made in a variety of different colors. It should not be confused with zircon, which is a zirconium silicate (ZrSiO4). It is sometimes erroneously called ''cubic zirconium''. Because of its low cost, durability, and close visual likeness to diamond, synthetic cubic zirconia has remained the most gemologically and economically important competitor for diamonds since commercial production began in 1976. Its main competitor as a synthetic gemstone is a more recently cultivated material, synthetic moissanite. Technical aspects Cubic zirconia is crystallographically isometric, an important attribute of a would-be diamond simulant. During synthesis zirconium oxide naturally forms monoclinic crystals, which are stable form under normal atmospheric conditions. A stabilizer is required for cubic crystals (taking on the fluorite structure) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science
Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for scientific reasoning is tens of thousands of years old. The earliest written records in the history of science come from Ancient Egypt and Mesopotamia in around 3000 to 1200 BCE. Their contributions to mathematics, astronomy, and medicine entered and shaped Greek natural philosophy of classical antiquity, whereby formal attempts were made to provide explanations of events in the physical world based on natural causes. After the fall of the Western Roman Empire, knowledge of Greek conceptions of the world deteriorated in Western Europe during the early centuries (400 to 1000 CE) of the Middle Ages, but was preserved in the Muslim world during the Islamic Golden Age and later by the efforts of Byzantine Greek scholars who brought Greek ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portable Refractometer
Portable may refer to: General * Portable building, a manufactured structure that is built off site and moved in upon completion of site and utility work * Portable classroom, a temporary building installed on the grounds of a school to provide additional classroom space where there is a shortage of capacity * Portable toilet, a modern, portable, self-contained outhouse manufactured of molded plastic Computing * Portable object (computing), a distributed computing term for an object which can be accessed through a normal method call while possibly residing in memory on another computer * Software portability, software that can easily be ported to multiple platforms * Portable applications, applications that do not require any kind of installation onto a computer, and can store data in the program's directory Electronics * Portable electronics * Portable device, a wearable or handheld device * Portable audio player, a personal electronic device that allows the user to listen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Refractometer
A refractometer is a laboratory or field device for the measurement of an Refractive index, index of refraction (refractometry). The index of refraction is calculated from the observed refraction angle using Snell's law. For mixtures, the index of refraction then allows to determine the concentration using mixing rules such as the Gladstone–Dale relation and Clausius–Mossotti_relation#Lorentz–Lorenz_equation, Lorentz–Lorenz equation. Refractometry Standard refractometers measure the extent of light refraction (as part of a refractive index) of transparent substances in either a liquid or solid-state; this is then used in order to identify a liquid sample, analyze the sample's purity, and determine the amount or concentration of dissolved substances within the sample. As light passes through the liquid from the air it will slow down and create a ‘bending’ illusion, the severity of the ‘bend’ will depend on the amount of substance dissolved in the liquid. For exam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
