A bead is a small, decorative object that is formed in a variety of shapes and sizes of a material such as stone, bone, shell, glass, plastic, wood, or pearl and with a small hole for threading or stringing. Beads range in size from under 1 millimeter (0.039 in) to over 1 centimeter (0.39 in) in diameter.
112-517: Beads represent some of the earliest forms of jewellery , with a pair of beads made from Nassarius sea snail shells dating to approximately 100,000 years ago thought to be the earliest known example. Beadwork is the art or craft of making things with beads. Beads can be woven together with specialized thread , strung onto thread or soft, flexible wire , or adhered to a surface (e.g. fabric , clay ). Beads can be divided into several types of overlapping categories based on different criteria such as
224-464: A chemical composition which includes what are referred to as absorption centers. Many substances are selective in their absorption of white light frequencies . They absorb certain portions of the visible spectrum while reflecting others. The frequencies of the spectrum which are not absorbed are either reflected or transmitted for our physical observation. This is what gives rise to color . The attenuation of light of all frequencies and wavelengths
336-447: A boundary at a steep angle, the light will be completely reflected. This effect, called total internal reflection , is used in optical fibers to confine light in the core. Light travels along the fiber bouncing back and forth off of the boundary. Because the light must strike the boundary with an angle greater than the critical angle , only light that enters the fiber within a certain range of angles will be propagated. This range of angles
448-647: A clear indicator of Greek influence in Etruscan jewellery. The modelling of heads, which was a typical practice from the Greek severe period, was a technique that spread throughout the Etruscan territory. An even clearer evidence of new influences is the shape introduced in the Orientalizing era: The Bullae. A pear-shaped vessel used to hold perfume. Its surface was usually decorated with repoussé and engraved symbolic figures. Transparency and translucency In
560-427: A fiber of silica glass that confines the incident light beam to the inside. In optical fibers, the main source of attenuation is scattering from molecular level irregularities, called Rayleigh scattering , due to structural disorder and compositional fluctuations of the glass structure . This same phenomenon is seen as one of the limiting factors in the transparency of infrared missile domes. Further attenuation
672-573: A high percentage of lead oxide in the glass formula, increasing the refractive index . Most of the other named glass types have their formulations and patterns inseparable from the manufacturing process. Small, colorful, fusible plastic beads can be placed on a solid plastic-backed peg array to form designs and then melted together with a clothes iron ; alternatively, they can be strung into necklaces and bracelets or woven into keychains. Fusible beads come in many colors and degrees of transparency / opacity , including varieties that glow in
784-400: A high transmission of ultraviolet light. Thus, when a material is illuminated, individual photons of light can make the valence electrons of an atom transition to a higher electronic energy level . The photon is destroyed in the process and the absorbed radiant energy is transformed to electric potential energy. Several things can happen, then, to the absorbed energy: It may be re-emitted by
896-486: A molten batch of glass of the desired color and pouring it into molds to form the desired shape. This is also true of most plastic beads. A smaller and more expensive subset of glass and lead crystal beads are cut into precise faceted shapes on an individual basis. This was once done by hand but has largely been taken over by precision machinery. "Fire-polished" faceted beads are a less expensive alternative to hand-cut faceted glass or crystal. They derive their name from
1008-572: A natural feel. However, any inclusion of lead or lead solder will give a British Assay office (the body which gives U.K. jewellery its stamp of approval, the Hallmark ) the right to destroy the piece, however, it is very rare for the assay office to do so. Beads are frequently used in jewellery. These may be made of glass, gemstones, metal, wood , shells, clay and polymer clay. Beaded jewellery commonly encompasses necklaces , bracelets , earrings , belts and rings . Beads may be large or small;
1120-540: A necklace design as a spacer however a necklace can be strung with just square beads. The necklaces with square beads are used in Rosary necklaces/prayer necklaces, and wooden or shell ones are made for beachwear. Elk rib bones were the original material for the long, tubular hair pipe beads. Today these beads are commonly made of bison and water buffalo bones and are popular for breastplates and chokers among Plains Indians . Black variations of these beads are made from
1232-403: A number of electrons (given by the atomic number Z in the periodic table ). Recall that all light waves are electromagnetic in origin. Thus they are affected strongly when coming into contact with negatively charged electrons in matter. When photons (individual packets of light energy) come in contact with the valence electrons of an atom, one of several things can and will occur: Most of
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#17327869559621344-527: A portion of the incoming light. The remaining frequencies (or wavelengths) are free to be reflected or transmitted. This is how colored glass is produced. Most liquids and aqueous solutions are highly transparent. For example, water, cooking oil, rubbing alcohol, air, and natural gas are all clear. Absence of structural defects (voids, cracks, etc.) and molecular structure of most liquids are chiefly responsible for their excellent optical transmission. The ability of liquids to "heal" internal defects via viscous flow
1456-462: A range of wavelengths. Guided light wave transmission via frequency selective waveguides involves the emerging field of fiber optics and the ability of certain glassy compositions to act as a transmission medium for a range of frequencies simultaneously ( multi-mode optical fiber ) with little or no interference between competing wavelengths or frequencies. This resonant mode of energy and data transmission via electromagnetic (light) wave propagation
1568-426: A regular lattice and a " sea of electrons " moving randomly between the atoms. In metals, most of these are non-bonding electrons (or free electrons) as opposed to the bonding electrons typically found in covalently bonded or ionically bonded non-metallic (insulating) solids. In a metallic bond, any potential bonding electrons can easily be lost by the atoms in a crystalline structure. The effect of this delocalization
1680-491: A relatively low cost. These components are free of internal stress or intrinsic birefringence , and allow relatively large doping levels or optimized custom-designed doping profiles. This makes ceramic laser elements particularly important for high-energy lasers. The development of transparent panel products will have other potential advanced applications including high strength, impact-resistant materials that can be used for domestic windows and skylights. Perhaps more important
1792-938: A responsible and modern alternative to mined diamonds. Retailers are responding to this trend by expanding their offerings of lab-grown diamond jewellery, further solidifying their place in the market. Many precious and semiprecious stones are used for jewellery. Among them are: Some gemstones (like pearls, coral, and amber) are classified as organic, meaning that they are produced by living organisms. Others are inorganic, meaning that they are generally composed of and arise from minerals. Some gems, for example, amethyst , have become less valued as methods of extracting and importing them have progressed. Some man-made gems can serve in place of natural gems, such as cubic zirconia , which can be used in place of diamonds. For platinum , gold , and silver jewellery, there are many techniques to create finishes. The most common are high-polish, satin/matte, brushed , and hammered. High-polished jewellery
1904-448: A ring can be classified: prong, bezel and tension setting. Synthetic diamonds, also referred to as lab-grown diamonds, are created using advanced technological processes such as High-Pressure High-Temperature (HPHT) and Chemical Vapor Deposition (CVD) . These methods result in diamonds that are chemically and physically identical to natural diamonds , offering the same brilliance and durability. The popularity of synthetic diamonds in
2016-602: A rounded steel hammer and hammering the jewellery to give it a wavy texture . Some jewellery is plated to give it a shiny, reflective look or to achieve a desired colour. Sterling silver jewellery may be plated with a thin layer of 0.999 fine silver (a process known as flashing) or plated with rhodium or gold. Base metal costume jewellery may also be plated with silver, gold, or rhodium for a more attractive finish. Jewellery has been used to denote status. In ancient Rome, only certain ranks could wear rings and later, sumptuary laws dictated who could wear what type of jewellery. This
2128-475: A status symbol, for its material properties, its patterns, or for meaningful symbols. Jewellery has been made to adorn nearly every body part, from hairpins to toe rings , and even genital jewellery . In modern European culture the amount worn by adult males is relatively low compared with other cultures and other periods in European culture. The word jewellery itself is derived from the word jewel , which
2240-573: A stone bracelet and marble ring are attributed to a similar age. Later, the European early modern humans had crude necklaces and bracelets of bone, teeth, berries, and stone hung on pieces of string or animal sinew , or pieces of carved bone used to secure clothing together. In some cases, jewellery had shell or mother-of-pearl pieces. A decorated engraved pendant (the Star Carr Pendant ) dating to around 11,000 BC, and thought to be
2352-648: A therapy for elderly homes; the pegboard later gained popularity as a toy for children. The bead designs were glued to cardboard or Masonite boards and used as trivets . Later, when the beads were made of polyethylene , it became possible to fuse them with a flat iron. Hama come in three sizes: mini (diameter 2 mm (0.079 in)), midi (5 mm (0.20 in)) and maxi (10 mm (0.39 in)). Perler beads come in two sizes called classic (5 mm) and biggie (10 mm). Pyssla beads (by IKEA ) only come in one size (5 mm). Modern mass-produced beads are generally shaped by carving or casting , depending on
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#17327869559622464-433: A trade-off between optical performance, mechanical strength and price. For example, sapphire (crystalline alumina ) is very strong, but it is expensive and lacks full transparency throughout the 3–5 μm mid-infrared range. Yttria is fully transparent from 3–5 μm, but lacks sufficient strength, hardness, and thermal shock resistance for high-performance aerospace applications. A combination of these two materials in
2576-699: A translucent frosted layer, applying an additional color layer, or both. Aurora Borealis , or AB, is a surface coating that diffuses light into a rainbow. Other surface coatings are vitrail, moonlight, dorado, satin, star shine, and heliotrope. Tagua nuts from South America are used as an ivory substitute since the natural ivory trade has been restricted worldwide. Jewellery Jewellery (or jewelry in American English ) consists of decorative items worn for personal adornment such as brooches , rings , necklaces , earrings , pendants , bracelets , and cufflinks . Jewellery may be attached to
2688-461: A two-to-one margin. In French and a few other European languages the equivalent term, joaillerie , may also cover decorated metalwork in precious metal such as objets d'art and church items, not just objects worn on the person. Humans have used jewellery for a number of different reasons: Most cultures at some point have had a practice of keeping large amounts of wealth stored in the form of jewellery. Numerous cultures store wedding dowries in
2800-419: A typical metal or ceramic object are in the form of grain boundaries , which separate tiny regions of crystalline order. When the size of the scattering center (or grain boundary) is reduced below the size of the wavelength of the light being scattered, the scattering no longer occurs to any significant extent. In the formation of polycrystalline materials (metals and ceramics) the size of the crystalline grains
2912-556: A war zone and sold to finance an insurgency . The British crown jewels contain the Cullinan Diamond , part of the largest gem-quality rough diamond ever found (1905), at 3,106.75 carats (621.35 g). Now popular in engagement rings , this usage dates back to the marriage of Maximilian I to Mary of Burgundy in 1477. A popular style is the diamond solitaire, which features a single large diamond mounted prominently. Within solitaire, there are three categories in which
3024-400: A woman's death it was sold at the souk and recycled or sold to passers-by. Islamic jewellery from before the 19th century is thus exceedingly rare. The history of jewellery is long and goes back many years, with many different uses among different cultures. It has endured for thousands of years and has provided various insights into how ancient cultures worked. The earliest known Jewellery
3136-460: Is also very popular in many African and indigenous North American cultures. Silversmiths , goldsmiths , and lapidaries use methods including forging , casting , soldering or welding , cutting, carving and "cold-joining" (using adhesives , staples and rivets to assemble parts). Diamonds were first mined in India . Pliny may have mentioned them, although there is some debate as to
3248-462: Is called the acceptance cone of the fiber. The size of this acceptance cone is a function of the refractive index difference between the fiber's core and cladding. Optical waveguides are used as components in integrated optical circuits (e.g., combined with lasers or light-emitting diodes , LEDs) or as the transmission medium in local and long-haul optical communication systems. Attenuation in fiber optics , also known as transmission loss ,
3360-481: Is caused by light absorbed by residual materials, such as metals or water ions, within the fiber core and inner cladding. Light leakage due to bending, splices, connectors, or other outside forces are other factors resulting in attenuation. At high optical powers, scattering can also be caused by nonlinear optical processes in the fiber. Many marine animals that float near the surface are highly transparent, giving them almost perfect camouflage . However, transparency
3472-508: Is dependent upon the frequency of the light, the nature of the atoms in the object, and often, the nature of the electrons in the atoms of the object. Some materials allow much of the light that falls on them to be transmitted through the material without being reflected. Materials that allow the transmission of light waves through them are called optically transparent. Chemically pure (undoped) window glass and clean river or spring water are prime examples of this. Materials that do not allow
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3584-416: Is determined largely by the size of the crystalline particles present in the raw material during formation (or pressing) of the object. Moreover, the size of the grain boundaries scales directly with particle size. Thus, a reduction of the original particle size well below the wavelength of visible light (about 1/15 of the light wavelength, or roughly 600 nm / 15 = 40 nm ) eliminates much of
3696-536: Is difficult for bodies made of materials that have different refractive indices from seawater. Some marine animals such as jellyfish have gelatinous bodies, composed mainly of water; their thick mesogloea is acellular and highly transparent. This conveniently makes them buoyant , but it also makes them large for their muscle mass, so they cannot swim fast, making this form of camouflage a costly trade-off with mobility. Gelatinous planktonic animals are between 50 and 90 percent transparent. A transparency of 50 percent
3808-423: Is due to the combined mechanisms of absorption and scattering . Transparency can provide almost perfect camouflage for animals able to achieve it. This is easier in dimly-lit or turbid seawater than in good illumination. Many marine animals such as jellyfish are highly transparent. With regard to the absorption of light, primary material considerations include: With regard to the scattering of light ,
3920-435: Is enough to make an animal invisible to a predator such as cod at a depth of 650 metres (2,130 ft); better transparency is required for invisibility in shallower water, where the light is brighter and predators can see better. For example, a cod can see prey that are 98 percent transparent in optimal lighting in shallow water. Therefore, sufficient transparency for camouflage is more easily achieved in deeper waters. For
4032-494: Is motion at the atomic and molecular levels. The primary mode of motion in crystalline substances is vibration . Any given atom will vibrate around some mean or average position within a crystalline structure, surrounded by its nearest neighbors. This vibration in two dimensions is equivalent to the oscillation of a clock's pendulum. It swings back and forth symmetrically about some mean or average (vertical) position. Atomic and molecular vibrational frequencies may average on
4144-405: Is one of the reasons why some fibrous materials (e.g., paper or fabric) increase their apparent transparency when wetted. The liquid fills up numerous voids making the material more structurally homogeneous. Light scattering in an ideal defect-free crystalline (non-metallic) solid that provides no scattering centers for incoming light will be due primarily to any effects of anharmonicity within
4256-401: Is relatively lossless. An optical fiber is a cylindrical dielectric waveguide that transmits light along its axis by the process of total internal reflection . The fiber consists of a core surrounded by a cladding layer. To confine the optical signal in the core, the refractive index of the core must be greater than that of the cladding. The refractive index is the parameter reflecting
4368-400: Is simply to exaggerate the effect of the "sea of electrons". As a result of these electrons, most of the incoming light in metals is reflected back, which is why we see a shiny metal surface. Most insulators (or dielectric materials) are held together by ionic bonds . Thus, these materials do not have free conduction electrons , and the bonding electrons reflect only a small fraction of
4480-465: Is that walls and other applications will have improved overall strength, especially for high-shear conditions found in high seismic and wind exposures. If the expected improvements in mechanical properties bear out, the traditional limits seen on glazing areas in today's building codes could quickly become outdated if the window area actually contributes to the shear resistance of the wall. Currently available infrared transparent materials typically exhibit
4592-660: Is the 'Gold Olive Wreath' (4th century BC), which is modeled on the type of wreath given as a prize for winners in athletic competitions like the Olympic Games. Jewellery dating from 600 to 475 BC is not well represented in the archaeological record, but after the Persian wars the quantity of jewellery again became more plentiful. One particularly popular type of design at this time was a bracelet decorated with snake and animal-heads Because these bracelets used considerably more metal, many examples were made from bronze. By 300 BC,
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4704-419: Is the most common and gives the metal a highly reflective, shiny look. Satin, or matte finish reduces the shine and reflection of the jewellery, and this is commonly used to accentuate gemstones such as diamonds . Brushed finishes give the jewellery a textured look and are created by brushing a material (similar to sandpaper) against the metal, leaving "brush strokes". Hammered finishes are typically created using
4816-406: Is the reduction in intensity of the light beam (or signal) with respect to distance traveled through a transmission medium. It is an important factor limiting the transmission of a signal across large distances. Attenuation coefficients in fiber optics usually use units of dB/km through the medium due to the very high quality of transparency of modern optical transmission media. The medium is usually
4928-423: Is usually sterling silver , or 92.5% fine silver. In costume jewellery , stainless steel findings are sometimes used. Other commonly used materials include glass , such as fused-glass or enamel ; wood , often carved or turned; shells and other natural animal substances such as bone and ivory ; natural clay ; polymer clay ; Hemp and other twines have been used as well to create jewellery that has more of
5040-677: The Royal Cemetery of Ur , where hundreds of burials dating 2900–2300 BC were unearthed; tombs such as that of Puabi contained a multitude of artefacts in gold, silver, and semi-precious stones, such as lapis lazuli crowns embellished with gold figurines, close-fitting collar necklaces, and jewel-headed pins. In Assyria , men and women both wore extensive amounts of jewellery, including amulets , ankle bracelets, heavy multi-strand necklaces, and cylinder seals . Jewellery in Mesopotamia tended to be manufactured from thin metal leaf and
5152-403: The speed of light in a material. (Refractive index is the ratio of the speed of light in vacuum to the speed of light in a given medium. The refractive index of vacuum is therefore 1.) The larger the refractive index, the more slowly light travels in that medium. Typical values for core and cladding of an optical fiber are 1.48 and 1.46, respectively. When light traveling in a dense medium hits
5264-724: The Berber cultures is a style of traditional jewellery worn by women and girls in the rural areas of the Maghreb region in North Africa inhabited by indigenous Berber people (in Berber language : Amazigh, Imazighen , pl). Following long social and cultural traditions, the silversmiths of different ethnic Berber groups of Morocco, Algeria and neighbouring countries created intricate jewellery to adorn their women and that formed part of their ethnic identity . Traditional Berber jewellery
5376-457: The Gods. They worked two styles of pieces: cast pieces and pieces hammered out of sheet metal. Fewer pieces of cast jewellery have been recovered. It was made by casting the metal onto two stone or clay moulds. The two-halves were then joined, and wax , followed by molten metal, was placed in the centre. This technique had been practised since the late Bronze Age . The more common form of jewellery
5488-655: The Great conquered part of it. In earlier designs, other European influences can also be detected. When Roman rule came to Greece, no change in jewellery designs was detected. However, by 27 BC, Greek designs were heavily influenced by the Roman culture. That is not to say that indigenous design did not thrive. Numerous polychrome butterfly pendants on silver foxtail chains, dating from the 1st century, have been found near Olbia , with only one example ever found anywhere else. Gorgons, pomegranates, acorns, lotus flowers and palms were
5600-566: The Greeks had mastered making coloured jewellery and using amethysts , pearl , and emeralds . Also, the first signs of cameos appeared, with the Greeks creating them from Indian Sardonyx , a striped brown pink and cream agate stone. Greek jewellery was often simpler than in other cultures, with simple designs and workmanship. However, as time progressed, the designs grew in complexity and different materials were soon used. Jewellery in Greece
5712-521: The Kurgan settlement of Yunatsite near Pazardzhik , the golden treasure Sakar, as well as beads and gold jewellery found in the Kurgan settlement of Provadia – Solnitsata ("salt pit"). However, Varna gold is most often called the oldest since this treasure is the largest and most diverse. By approximately 5,000 years ago, jewellery-making had become a significant craft in the cities of Mesopotamia . The most significant archaeological evidence comes from
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#17327869559625824-580: The Museum of Ancient History in Lower Austria revealed that they had found a grave of a female jewellery worker – forcing archaeologists to take a fresh look at prehistoric gender roles after it appeared to be that of a female fine metal worker – a profession that was previously thought to have been carried out exclusively by men. The first signs of established jewellery making in Ancient Egypt
5936-614: The Mycenaean period, but unfortunately this skill was lost at the end of the Bronze Age. The forms and shapes of jewellery in ancient Greece such as the armring (13th century BC), brooch (10th century BC) and pins (7th century BC), have varied widely since the Bronze Age as well. Other forms of jewellery include wreaths, earrings, necklace and bracelets. A good example of the high quality that gold working techniques could achieve in Greece
6048-448: The U.S. featured a double-ring ceremony, up from 15% in the 1920s. Some religions have specific rules or traditions surrounding jewellery (or even prohibiting it) and many religions have edicts against excessive display. Islam, for instance, considers the wearing of gold by men as Haraam . The majority of Islamic jewellery was in the form of bridal dowries , and traditionally was not handed down from generation to generation; instead, on
6160-830: The Western practice of married people wearing wedding rings). Wearing of amulets and devotional medals to provide protection or to ward off evil is common in some cultures. These may take the form of symbols (such as the ankh ), stones, plants, animals, body parts (such as the Khamsa ), or glyphs (such as stylised versions of the Throne Verse in Islamic art ). In creating jewellery, gemstones , coins , or other precious items are often used, and they are typically set into precious metals . Platinum alloys range from 900 (90% pure) to 950 (95% pure). The silver used in jewellery
6272-460: The animals' horns. Seed beads are uniformly shaped spheroidal or tube shaped beads ranging in size from under a millimetre to several millimetres. "Seed bead" is a generic term for any small bead. Usually rounded in shape, seed beads are most commonly used for loom and off-loom bead weaving. Tibetan Dzi beads and Rudraksha beads are used to make Buddhist and Hindu rosaries ( malas ). Magatama are traditional Japanese beads, and cinnabar
6384-425: The body of the resulting beads, which are then primarily referred to by the glass type. If the glass batch is used to create a large massive block instead of pre-shaping it as it cools, the result may then be carved into smaller items in the same manner as stone. Conversely, glass artisans may make beads by lampworking the glass on an individual basis; once formed, the beads undergo little or no further shaping after
6496-469: The body or the clothes. From a western perspective, the term is restricted to durable ornaments , excluding flowers for example. For many centuries metal such as gold often combined with gemstones , has been the normal material for jewellery, but other materials such as glass, shells and other plant materials may be used. Jewellery is one of the oldest types of archaeological artefact – with 100,000-year-old beads made from Nassarius shells thought to be
6608-479: The center in putting through a string to hold the beads together using different techniques that can help. Some archaeologists had been working at Blombos cave located in South Africa, there was a recent discovery showing forty-one marine shell ( Nassarius kraussianus ) beads. It was estimated that it was made about seventy-five thousand years ago. Most glass beads are pressed glass , mass-produced by preparing
6720-578: The dark or have internal glitter ; peg boards come in various shapes and several geometric patterns. Plastic toy beads, made by chopping plastic tubes into short pieces, were introduced in 1958 by Munkplast AB in Munka-Ljungby , Sweden. Known as Indian beads , they were originally sewn together to form ribbons. The pegboard for bead designs was invented in the early 1960s (patented 1962, patent granted 1967) by Gunnar Knutsson in Vällingby, Sweden, as
6832-472: The electron as radiant energy (in this case, the overall effect is in fact a scattering of light), dissipated to the rest of the material (i.e., transformed into heat ), or the electron can be freed from the atom (as in the photoelectric effects and Compton effects ). The primary physical mechanism for storing mechanical energy of motion in condensed matter is through heat , or thermal energy . Thermal energy manifests itself as energy of motion. Thus, heat
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#17327869559626944-476: The emerging chemical processing methods encompassed by the methods of sol-gel chemistry and nanotechnology . Transparent ceramics have created interest in their applications for high energy lasers, transparent armor windows, nose cones for heat seeking missiles, radiation detectors for non-destructive testing, high energy physics, space exploration, security and medical imaging applications. Large laser elements made from transparent ceramics can be produced at
7056-470: The exact nature of the stone he referred to as Adamas . In 2005, Australia , Botswana , Russia and Canada ranked among the primary sources of gemstone diamond production. There are negative consequences of the diamond trade in certain areas. Diamonds mined during the recent civil wars in Angola , Ivory Coast , Sierra Leone , and other nations have been labeled as blood diamonds when they are mined in
7168-500: 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
7280-620: The five fingers of the hand and is traditionally believed both by Muslims as well as Jewish people to protect against the evil eye . The oldest gold jewellery in the world is dating from 4,600 BC to 4,200 BC and was discovered in Europe, at the site of Varna Necropolis , near the Black Sea coast in Bulgaria . Several prehistoric Bulgarian finds are considered no less old – the golden treasures of Hotnitsa, Durankulak , artifacts from
7392-439: The form of jewellery or make jewellery as a means to store or display coins. Alternatively, jewellery has been used as a currency or trade good to buy and sell. an example being the use of slave beads . Many items of jewellery, such as brooches and buckles , originated as purely functional items, but evolved into decorative items as their functional requirement diminished. Similarly, Tiffany & Co . produced inkwells in
7504-561: The form of the yttrium aluminium garnet (YAG) is one of the top performers in the field. When light strikes an object, it usually has not just a single frequency (or wavelength) but many. Objects have a tendency to selectively absorb, reflect, or transmit light of certain frequencies. That is, one object might reflect green light while absorbing all other frequencies of visible light. Another object might selectively transmit blue light while absorbing all other frequencies of visible light. The manner in which visible light interacts with an object
7616-411: The frequency of the incoming light wave is at or near the energy levels of the electrons within the atoms that compose the substance. In this case, the electrons will absorb the energy of the light wave and increase their energy state, often moving outward from the nucleus of the atom into an outer shell or orbital . The atoms that bind together to make the molecules of any particular substance contain
7728-410: The frequency of the light wave and the physical dimension of the scattering center. For example, since visible light has a wavelength scale on the order of a micrometre, scattering centers will have dimensions on a similar spatial scale. Primary scattering centers in polycrystalline materials include microstructural defects such as pores and grain boundaries. In addition to pores, most of the interfaces in
7840-505: The grain. There are also several ways to fuse many small glass canes together into a multicolored pattern, resulting in millefiori beads or chevron beads (sometimes called "trade beads"). "Furnace glass" beads encase a multicolored core in a transparent exterior layer which is then annealed in a furnace. More economically, millefiori beads can also be made by limiting the patterning process to long, narrow canes or rods known as murrine. Thin cross-sections, or "decals", can then be cut from
7952-407: The incident wave. The remaining frequencies (or wavelengths) are free to propagate (or be transmitted). This class of materials includes all ceramics and glasses . If a dielectric material does not include light-absorbent additive molecules (pigments, dyes, colorants), it is usually transparent to the spectrum of visible light. Color centers (or dye molecules, or " dopants ") in a dielectric absorb
8064-771: The involved aspects. When light encounters a material, it can interact with it in several different ways. These interactions depend on the wavelength of the light and the nature of the material. Photons interact with an object by some combination of reflection, absorption and transmission. Some materials, such as plate glass and clean water , transmit much of the light that falls on them and reflect little of it; such materials are called optically transparent. Many liquids and aqueous solutions are highly transparent. Absence of structural defects (voids, cracks, etc.) and molecular structure of most liquids are mostly responsible for excellent optical transmission. Materials that do not transmit light are called opaque . Many such substances have
8176-614: The jewellery had significance. Green, for example, symbolised fertility. Lapis lazuli and silver had to be imported from beyond the country's borders. Egyptian designs were most common in Phoenician jewellery. Also, ancient Turkish designs found in Persian jewellery suggest that trade between the Middle East and Europe was not uncommon. Women wore elaborate gold and silver pieces that were used in ceremonies. Jewellery of
8288-465: The jewellery market has increased significantly due to several factors. Their typically lower price compared to natural diamonds makes them an appealing choice for many consumers. Additionally, the ethical implications of synthetic diamonds have garnered attention, particularly their potential to eliminate the risks associated with conflict diamonds , which are mined in war zones and often used to finance armed conflict. From an environmental perspective,
8400-530: The late 19th and early 20th centuries, skillfully combining materials like enamel and fine metals, reflecting the same craftsmanship seen in their jewellery collections. These inkwells were not only practical but also artistic in design. Jewellery can symbolise group membership (as in the case, of the Christian crucifix or the Jewish Star of David ) or status (as in the case of chains of office , or
8512-445: The layers have been properly annealed . Most of these glass subtypes are some form of fused glass , although goldstone is created by controlling the reductive atmosphere and cooling conditions of the glass batch rather than by fusing separate components together. Dichroic glass beads incorporate a semitransparent microlayer of metal between two or more layers. Fibre optic glass beads have an eyecatching chatoyant effect across
8624-510: The light scattering, resulting in a translucent or even transparent material. Computer modeling of light transmission through translucent ceramic alumina has shown that microscopic pores trapped near grain boundaries act as primary scattering centers. The volume fraction of porosity had to be reduced below 1% for high-quality optical transmission (99.99 percent of theoretical density). This goal has been readily accomplished and amply demonstrated in laboratories and research facilities worldwide using
8736-401: 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 the 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
8848-440: The material (e.g., the grain boundaries of a polycrystalline material or the cell or fiber boundaries of an organic material), and by its surface, if it is rough. Diffuse reflection is typically characterized by omni-directional reflection angles. Most of the objects visible to the naked eye are identified via diffuse reflection. Another term commonly used for this type of reflection is "light scattering". Light scattering from
8960-456: The material and desired effect. In some cases, more specialized metalworking or glassworking techniques may be employed, or a combination of multiple techniques and materials may be used such as in cloisonné . Beads are small circular shapes that come in different shapes and sizes. The materials are made from different qualities such as color, shape, shine, pattern, or even exotic materials used, etc. In making beads, they have to have holes in
9072-413: The material and re-emitted on the opposite side of the object. Such frequencies of light waves are said to be transmitted. An object may be not transparent either because it reflects the incoming light or because it absorbs the incoming light. Almost all solids reflect a part and absorb a part of the incoming light. When light falls onto a block of metal , it encounters atoms that are tightly packed in
9184-580: The materials from which they are made, the process used in their manufacturing, the place or period of origin, the patterns on their surface, or their general shape. In some cases, such as millefiori and cloisonné beads, multiple categories may overlap in an interdependent fashion. Beads can be made of many different materials. The earliest beads were made of a variety of natural materials which, after they were gathered, could be readily drilled and shaped. As humans became capable of obtaining and working with more difficult materials, those materials were added to
9296-406: The most critical factor is the length scale of any or all of these structural features relative to the wavelength of the light being scattered. Primary material considerations include: Diffuse reflection - Generally, when light strikes the surface of a (non-metallic and non-glassy) solid material, it bounces off in all directions due to multiple reflections by the microscopic irregularities inside
9408-441: The murrine and fused into the surface of a plain glass bead. Beads can be made in variety of shapes, including the following, as well as tubular and oval-shaped beads. This is the most common shape of beads that are strung on wire to create necklaces, and bracelets. The shape of the round beads lay together and are pleasing to the eye. Round beads can be made of glass, stone, ceramic, metal, or wood. Square beads can be to enhance
9520-522: The oldest Mesolithic art in Britain, was found at the site of Star Carr in North Yorkshire in 2015. In southern Russia , carved bracelets made of mammoth tusk have been found. The Venus of Hohle Fels features a perforation at the top, showing that it was intended to be worn as a pendant . Around seven thousand years ago, the first sign of copper jewellery was seen. In October 2012,
9632-602: The oldest known jewellery. The basic forms of jewellery vary between cultures but are often extremely long-lived; in European cultures the most common forms of jewellery listed above have persisted since ancient times, while other forms such as adornments for the nose or ankle, important in other cultures, are much less common. Jewellery may be made from a wide range of materials. Gemstones and similar materials such as amber and coral , precious metals , beads , and shells have been widely used, and enamel has often been important. In most cultures jewellery can be understood as
9744-443: The order of 0.5 μm . Scattering centers (or particles) as small as 1 μm have been observed directly in the light microscope (e.g., Brownian motion ). Optical transparency in polycrystalline materials is limited by the amount of light scattered by their microstructural features. Light scattering depends on the wavelength of the light. Limits to spatial scales of visibility (using white light) therefore arise, depending on
9856-460: The order of 10 cycles per second ( Terahertz radiation ). When a light wave of a given frequency strikes a material with particles having the same or (resonant) vibrational frequencies, those particles will absorb the energy of the light wave and transform it into thermal energy of vibrational motion. Since different atoms and molecules have different natural frequencies of vibration, they will selectively absorb different frequencies (or portions of
9968-430: The ordered lattice. Light transmission will be highly directional due to the typical anisotropy of crystalline substances, which includes their symmetry group and Bravais lattice . For example, the seven different crystalline forms of quartz silica ( silicon dioxide , SiO 2 ) are all clear, transparent materials . Optically transparent materials focus on the response of a material to incoming light waves of
10080-430: The overall appearance of one color, or any combination leading up to a brilliant spectrum of every color. The opposite property of translucency is opacity . Other categories of visual appearance, related to the perception of regular or diffuse reflection and transmission of light, have been organized under the concept of cesia in an order system with three variables, including transparency, translucency and opacity among
10192-505: The production of synthetic diamonds generally has a smaller ecological footprint than traditional diamond mining , which can result in extensive land degradation and habitat destruction. While lab-grown diamonds do require energy for their production, many companies are actively adopting renewable energy sources to mitigate their environmental impact. As consumer preferences evolve, particularly among younger generations who prioritize sustainability, synthetic diamonds are increasingly seen as
10304-918: The range of available substances. Beads were a part of different cultures, each made with different materials throughout history and using beads to form something handmade. Beads came in different colors, shapes, and forms, what materials were used, and whether there was a meaning or meaning behind the beads. In modern manufacturing, the most common bead materials are wood , plastic , glass , metal , and stone . Beads are still made from many naturally occurring materials, both organic (i.e., of animal - or plant -based origin) and inorganic (purely mineral origin). However, some of these materials now routinely undergo some extra processing beyond mere shaping and drilling such as color enhancement via dyes or irradiation. The natural organics include bone , coral , horn , ivory , seeds (such as tagua nuts), animal shells , and wood . For most of human history, pearls were
10416-422: The second half of a two-part process: first, the glass batch is poured into round bead molds, then they are faceted with a grinding wheel. The faceted beads are then poured onto a tray and briefly reheated just long enough to melt the surface, "polishing" out any minor surface irregularities from the grinding wheel. There are several specialized glassworking techniques that create a distinctive appearance throughout
10528-417: The slang term bling-bling , which refers to the ostentatious display of jewellery by men or women. Conversely, the jewellery industry in the early 20th century launched a campaign to popularise wedding rings for men, which caught on, as well as engagement rings for men, which did not, go so far as to create a false history and claim that the practice had medieval roots. By the mid-1940s, 85% of weddings in
10640-482: The smallest type of beads used are known as seed beads , these are the beads used for the "woven" style of beaded jewellery. Seed beads are also used in an embroidery technique where they are sewn onto fabric backings to create broad collar neck pieces and beaded bracelets. Bead embroidery, a popular type of handwork during the Victorian era , is enjoying a renaissance in modern jewellery making. Beading, or beadwork,
10752-407: The spectrum) of infrared light. Reflection and transmission of light waves occur because the frequencies of the light waves do not match the natural resonant frequencies of vibration of the objects. When infrared light of these frequencies strikes an object, the energy is reflected or transmitted. If the object is transparent, then the light waves are passed on to neighboring atoms through the bulk of
10864-407: The surfaces of objects is our primary mechanism of physical observation. Light scattering in liquids and solids depends on the wavelength of the light being scattered. Limits to spatial scales of visibility (using white light) therefore arise, depending on the frequency of the light wave and the physical dimension (or spatial scale) of the scattering center. Visible light has a wavelength scale on
10976-586: The time, it is a combination of the above that happens to the light that hits an object. The states in different materials vary in the range of energy that they can absorb. Most glasses, for example, block ultraviolet (UV) light. What happens is the electrons in the glass absorb the energy of the photons in the UV range while ignoring the weaker energy of photons in the visible light spectrum. But there are also existing special glass types, like special types of borosilicate glass or quartz that are UV-permeable and thus allow
11088-584: The trade and manufacture of jewellery have also been unearthed throughout Mesopotamian archaeological sites. One record in the Mari royal archives, for example, gives the composition of various items of jewellery: The Greeks started using gold and gems in jewellery in 1600 BC, although beads shaped as shells and animals were produced widely in earlier times. Around 1500 BC, the main techniques of working gold in Greece included casting, twisting bars, and making wire. Many of these sophisticated techniques were popular in
11200-469: The transmission of any light wave frequencies are called opaque . Such substances may have a chemical composition which includes what are referred to as absorption centers. Most materials are composed of materials that are selective in their absorption of light frequencies. Thus they absorb only certain portions of the visible spectrum. The frequencies of the spectrum which are not absorbed are either reflected back or transmitted for our physical observation. In
11312-1024: The ultimate precious beads of natural origin because of their rarity; the modern pearl-culturing process has made them far more common. Amber and jet are also of natural organic origin although both are the result of partial fossilization . The natural inorganics include various types of stones , ranging from gemstones to common minerals , and metals . Of the latter, only a few precious metals occur in pure forms, but other purified base metals may as well be placed in this category along with certain naturally occurring alloys such as electrum . The oldest-surviving synthetic materials used for bead making have generally been ceramics : pottery and glass . Beads were also made from ancient alloys such as bronze and brass , but as those were more vulnerable to oxidation they have generally been less well-preserved at archaeological sites. Many different subtypes of glass are now used for beadmaking, some of which have their component-specific names. Lead crystal beads have
11424-535: The visible portion of the spectrum, this is what gives rise to color. Absorption centers are largely responsible for the appearance of specific wavelengths of visible light all around us. Moving from longer (0.7 μm) to shorter (0.4 μm) wavelengths: Red, orange, yellow, green, and blue (ROYGB) can all be identified by our senses in the appearance of color by the selective absorption of specific light wave frequencies (or wavelengths). Mechanisms of selective light wave absorption include: In electronic absorption,
11536-604: The world, beads are used for symbolic purposes, for example: Beads are thought to be one of the earliest forms of trade between members of the human race. It is believed that bead trading was one of the reasons why humans developed language. Beads are said to have been used and traded for most of human history. The oldest beads found to date were at Blombos Cave , about 72,000 years old, and at Ksar Akil in Lebanon, about 40,000 years old. After shaping, glass and crystal beads can have their surface appearance enhanced by etching
11648-590: Was anglicised from the Old French " jouel ", and beyond that, to the Latin word " jocale ", meaning plaything. In British English , Indian English , New Zealand English , Hiberno-English , Australian English , and South African English it is spelled jewellery. At the same time, the spelling is jewelry in American English . Both are used in Canadian English . However, jewellery prevails by
11760-518: Was actually created not by modern humans ( Homo sapiens ) but by Neanderthal living in Europe. Specifically, perforated beads made from small seashells have been found dating to 115,000 years ago in the Cueva de los Aviones, a cave along the southeast coast of Spain. Later in Kenya, at Enkapune Ya Muto , beads made from perforated ostrich eggshells have been dated to more than 40,000 years ago. In Russia,
11872-465: Was also based on the rank of the citizens of that time. Cultural dictates have also played a significant role. For example, the wearing of earrings by Western men was considered effeminate in the 19th century and early 20th century. More recently, the display of body jewellery, such as piercings , has become a mark of acceptance or seen as a badge of courage within some groups but is completely rejected in others. Likewise, hip hop culture has popularised
11984-484: Was around 3,000–5,000 years ago. The Egyptians preferred the luxury, rarity, and workability of gold over other metals. In Predynastic Egypt jewellery soon began to symbolise political and religious power in the community. Although it was worn by wealthy Egyptians in life, it was also worn by them in death, with jewellery commonly placed among grave goods . In conjunction with gold jewellery, Egyptians used coloured glass , along with semi-precious gems. The colour of
12096-441: Was hardly worn and was mostly used for public appearances or on special occasions. It was frequently given as a gift and was predominantly worn by women to show their wealth, social status, and beauty. The jewellery was often supposed to give the wearer protection from the " evil eye " or endowed the owner with supernatural powers , while others had a religious symbolism. Older pieces of jewellery that have been found were dedicated to
12208-588: Was often used for making beads in China . Wampum are cylindrical white or purple beads made from quahog or North Atlantic channeled whelk shells by northeastern Native American tribes, such as the Wampanoag and Shinnecock . Job's tears are seed beads popular among southeastern Native American tribes. Heishe are beads made of shells or stones by the Kewa Pueblo people of New Mexico . In many parts of
12320-457: Was set with large numbers of brightly coloured stones (chiefly agate, lapis, carnelian, and jasper). Favoured shapes included leaves, spirals, cones, and bunches of grapes. Jewellers created works both for human use and for adorning statues and idols. They employed a wide variety of sophisticated metalworking techniques, such as cloisonné , engraving , fine granulation , and filigree . Extensive and meticulously maintained records pertaining to
12432-491: Was the hammered sheet type. Sheets of metal would be hammered to thickness and then soldered together. The inside of the two sheets would be filled with wax or another liquid to preserve the metal work. Different techniques, such as using a stamp or engraving, were then used to create motifs on the jewellery. Jewels may then be added to hollows or glass poured into special cavities on the surface. The Greeks took much of their designs from outer origins, such as Asia, when Alexander
12544-465: Was usually made of silver and includes elaborate brooches made of triangular plates and pins ( fibula ), originally used as clasps for garments, but also necklaces, bracelets, earrings and similar items. Another major type is the so-called khmissa (local pronunciation of the Arabic word "khamsa" for the number "five"), which is called afus in the Berber language ( Tamazight) . This form represents
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