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GEM (Den Haag)
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 W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cardinal Gems
Cardinal gems are gemstones which have traditionally been considered precious above all others. The classification of the cardinal gems dates back to antiquity, and was largely determined by ceremonial or religious use and rarity. The term has largely fallen out of use. The five traditional cardinal gems are: * amethyst (purple) – Rare and precious in the Old World until large deposits were found in Brazil. *diamond (transparent) *emerald (green) *ruby (red) *sapphire Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, chromium, vanadium, or magnesium. The name sapphire is derived via the Latin "sapphir ... (blue) References Gemology {{mineral-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engraved Gem
An engraved gem, frequently referred to as an intaglio, is a small and usually semi-precious gemstone that has been carved, in the Western tradition normally with images or inscriptions only on one face. The engraving of gemstones was a major luxury art form in the Ancient world, and an important one in some later periods. Strictly speaking, ''engraving'' means carving ''in intaglio'' (with the design cut ''into'' the flat background of the stone), but relief carvings (with the design projecting ''out of'' the background as in nearly all cameos) are also covered by the term. This article uses ''cameo'' in its strict sense, to denote a carving exploiting layers of differently coloured stone. The activity is also called ''gem carving'' and the artists ''gem-cutters''. References to antique gems and intaglios in a jewellery context will almost always mean carved gems; when referring to monumental sculpture, counter-relief, meaning the same as ''intaglio'', is more likely to be use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Translucency
In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale (one in which the dimensions are much larger than the wavelengths of the photons in question), the photons can be said to follow Snell's law. Translucency (also called translucence or translucidity) allows light to pass through, but does not necessarily (again, on the macroscopic scale) follow Snell's law; the photons can be scattered at either of the two interfaces, or internally, where there is a change in index of refraction. In other words, a translucent material is made up of components with different indices of refraction. A transparent material is made up of components with a uniform index of refraction. Transparent materials appear clear, with the overall appearance of one color, or any combination leading up to a brilliant spectrum of every color. The opposite ... [...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] |
Translucent
In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale (one in which the dimensions are much larger than the wavelengths of the photons in question), the photons can be said to follow Snell's law. Translucency (also called translucence or translucidity) allows light to pass through, but does not necessarily (again, on the macroscopic scale) follow Snell's law; the photons can be scattered at either of the two interfaces, or internally, where there is a change in index of refraction. In other words, a translucent material is made up of components with different indices of refraction. A transparent material is made up of components with a uniform index of refraction. Transparent materials appear clear, with the overall appearance of one color, or any combination leading up to a brilliant spectrum of every color. The opposite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sapphire
Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, chromium, vanadium, or magnesium. The name sapphire is derived via the Latin "sapphirus" from the Greek "sappheiros", which referred to Lapis lazuli, lapis lazuli. It is typically blue, but natural "fancy" sapphires also occur in yellow, purple, orange, and green colors; "parti sapphires" show two or more colors. Red corundum stones also occur, but are called ruby, rubies rather than sapphires. Pink-colored corundum may be classified either as ruby or sapphire depending on locale. Commonly, natural sapphires are cut and polished into gemstones and worn in jewellery, jewelry. They also may be created synthetically in laboratories for industrial or decorative purposes in large boule (crystal), crystal boules. Because of the remarkable hardness of sapphires 9 on the Mohs scale of mineral hardness, Mohs scale (the third hardest ... [...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] |
Emerald
Emerald is a gemstone and a variety of the mineral beryl (Be3Al2(SiO3)6) colored green by trace amounts of chromium or sometimes vanadium.Hurlbut, Cornelius S. Jr. and Kammerling, Robert C. (1991) ''Gemology'', John Wiley & Sons, New York, p. 203, . Beryl has a hardness of 7.5–8 on the Mohs scale. Most emeralds are highly included, so their toughness (resistance to breakage) is classified as generally poor. Emerald is a cyclosilicate. Etymology The word "emerald" is derived (via fro, esmeraude and enm, emeraude), from Vulgar Latin: ''esmaralda''/''esmaraldus'', a variant of Latin ''smaragdus'', which was a via grc, σμάραγδος (smáragdos; "green gem") from a Semitic language. According to Webster's Dictionary the term emerald was first used in the 14th century. Properties determining value Emeralds, like all colored gemstones, are graded using four basic parameters–the four ''C''s of connoisseurship: ''color'', ''clarity,'' ''cut'' and ''carat weight''. N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greece
Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of culturally and linguistically related city-states and other territories. Most of these regions were officially unified only once, for 13 years, under Alexander the Great's empire from 336 to 323 BC (though this excludes a number of Greek city-states free from Alexander's jurisdiction in the western Mediterranean, around the Black Sea, Cyprus, and Cyrenaica). In Western history, the era of classical antiquity was immediately followed by the Early Middle Ages and the Byzantine period. Roughly three centuries after the Late Bronze Age collapse of Mycenaean Greece, Greek urban poleis began to form in the 8th century BC, ushering in the Archaic period and the colonization of the Mediterranean Basin. This was followed by the age of Classical G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diamantaire
A diamantaire (''French origin'') is a gem-quality diamond manufacturer or producer, master diamond cutter, and graduate gemologist specializing in diamonds. Such individuals demonstrate considerable expertise in different types of gemstones, particularly when it comes to increasing the value and quality of a rough or raw diamond. They are highly skilled craftsmen or artisans who are responsible for cutting, polishing and transforming a rough diamond into a finished gemstone ready for setting. Members of diamond dealing families who have established themselves in the upper echelons of the world diamond industry hierarchy are also often referred to as ''diamantaires'' as well. See also *Diamond cutting * Rockwell Diamonds Rockwell Diamonds was a mid-tier diamond mining and development company. The company had an interest in producing and exploration alluvial diamond properties in southern Africa. The stock of the company once traded on the South African, Canadian, ... Refere ... [...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] |
Gemcutter
Lapidary (from the Latin ) is the practice of shaping stone, minerals, or gemstones into decorative items such as cabochons, engraved gems (including cameos), and faceted designs. A person who practices lapidary is known as a lapidarist. A lapidarist uses the lapidary techniques of cutting, grinding, and polishing. Hardstone carving requires specialized carving techniques. In modern contexts, a gemcutter is a person who specializes in cutting diamonds, but in older contexts the term refers to artists who produced hardstone carvings; engraved gems such as jade carvings, a branch of miniature sculpture or ornament in gemstone. By extension, the term ''lapidary'' has sometimes been applied to collectors of and dealers in gems, or to anyone who is knowledgeable in precious stones. Etymology The etymological root of the word 'lapidary' is the Latin word , meaning "stone".Douglas Harper (2014)Lapidary Online Etymology Dictionary In the 14th century, the term evolved from , meanin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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