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Jewelry and Gemstones

Jewelry and Gemstones

Jewellery has been used for a number of reasons:

  • Currency, wealth display and storage,
  • Functional use (such as clasps, pins and buckles)
  • Symbolism (to show membership or status)
  • Protection (in the form of amulets and magical wards),[3]
  • Artistic display

Most cultures have at some point had a practice of keeping large amounts of wealth stored in the form of jewellery. Numerous cultures move wedding dowries in the form of jewellery, or create jewellery as a means to store or display coins. Alternatively, jewellery has been used as a currency or trade good; an example being the use of slave beads.[citation needed]

Many items of jewellery, such as brooches and buckles originated as purely functional items, but evolved into decorative items as their functional requirement diminished.[4]

Jewellery can also be symbolic of group membership, as in the case of the Christian crucifix or Jewish Star of David, or of status, as in the case of chains of office, or the Western practice of married people wearing a wedding ring.

Wearing of amulets and devotional medals to provide protection or ward off evil is common in some cultures; these may take the form of symbols (such as theankh), stones, plants, animals, body parts (such as the Khamsa), or glyphs (such as stylised versions of the Throne Verse in Islamic art).[5]

Although artistic display has clearly been a function of jewellery from the very beginning, the other roles described above tended to take primacy.[citation needed] It was only in the late 19th century, with the work of such masters as Peter Carl Fabergé and René Lalique, that art began to take primacy over function and wealth.[citation needed] This trend has continued into modern times, expanded upon by artists such as Robert Lee Morris, Ed Levin, and Alberto Repossi.

Materials and methods

In creating jewellery, gemstones, coins, or other precious items are often used, and they are typically set into precious metals. Alloys of nearly every metal known have been encountered in jewellery - bronze, for example, was common in Roman times. Modern fine jewellery usually includes gold, white gold, platinum,palladium, titanium or silver. Most American and European gold jewellery is made of an alloy of gold, the purity of which is stated in karats, indicated by a number followed by the letter K. American gold jewellery must be of at least 10K purity (41.7% pure gold), (though in the UK the number is 9K (37.5% pure gold) and is typically found up to 18K (75% pure gold). Higher purity levels are less common with alloys at 22 K (91.6% pure gold), and 24 K (99.9% pure gold) being considered too soft for jewellery use in America and Europe. These high purity alloys, however, are widely used across Asia, the Middle East and Africa.[citation needed] Platinum alloys range from 900 (90% pure) to 950 (95.0% pure). The silver used in jewellery is usually sterling silver, or 92.5% fine silver. In costume jewellery, stainless steelfindings 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; and even plastics. Hemp and other twines have been used as well to create jewellery that has more of a natural feel. However, any inclusion of lead or lead solder will cause an English Assay office (the building which gives English jewellery its stamp of approval, the Hallmark) to destroy the piece.[citation needed]

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, the smallest type of beads used are known as seed beads, these are the beads used for the “woven” style of beaded jewellery. Another use of seed beads is an embroidery technique where seed beads 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, is also very popular in many African cultures.

Advanced glass and glass beadmaking techniques by Murano and Venetian glassmasters developed crystalline glass, enamelled glass (smalto), glass with threads of gold (goldstone), multicoloured glass (millefiori), milk-glass (lattimo) and imitation gemstones made of glass.[citation needed] As early as the 13th century, Murano glass and Murano beads were popular.[citation needed]

Silversmiths, goldsmiths, and lapidaries methods include forging, casting, soldering or welding, cutting, carving and “cold-joining” (using adhesives, staples andrivets to assemble parts).[6]

Gemstones

gemstone or gem (also called a precious or semi-precious stone, or jewel) is a piece of mineral, which, in cut and polished form, is used to makejewelry or other adornments.[1][2] However certain rocks, (such as lapis lazuli) and organic materials (such as amber or jet) are not minerals, but are still 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 theirlustre or other physical properties that have aesthetic value. Rarity is another characteristic that lends value to a gemstone. Apart from jewelry, from earliest antiquity until the 19th century engraved gems and hardstone carvings such as cups were major luxury art forms; the carvings of Carl Fabergé were the last significant works in this tradition.

Many precious and semiprecious stones are used for jewellery. Among them are:

  • Amber, an ancient organic gemstone, is composed of tree resin that has hardened over time. The stone must be at least 1 million years old to be classified as amber, and some amber can be up to 120 million years old.
  • Amethyst has historically been the most prized gemstone in the quartz family. It is treasured for its purple hue, which can range in tone from light to dark.
  • Emeralds are one of the three main precious gemstones (along with rubies and sapphires) and are known for their fine green to bluish green colour. They have been treasured throughout history, and some historians report that the Egyptians mined emerald as early as 3500 BC.
  • Jade is most commonly associated with the colour green, but can come in a number of other colours as well. Jade is closely linked to Asian culture, history, and tradition, and is sometimes referred to as the stone of heaven.
  • Jasper is a gemstone of the chalcedony family that comes in a variety of colours. Often, jasper will feature unique and interesting patterns within the coloured stone. Picture jasper is a type of jasper known for the colours (often beiges and browns) and swirls in the stone’s pattern.
  • Quartz refers to a family of crystalline gemstones of various colours and sizes. Among the well-known types of quartz are rose quartz (which has a delicate pink colour), and smoky quartz (which comes in a variety of shades of translucent brown). A number of other gemstones, like Amethyst and Citrine, are also part of the quartz family. Rutilated quartz is a popular type of quartz containing needle-like inclusions.
  • Rubies are known for their intense red colour, and are among the most highly valued precious gemstones. Rubies have been treasured for millennia. In Sanskrit, the word for ruby is ratnaraj, meaning king of precious stones.
  • Sapphire. The most popular form of sapphire is blue sapphire, which is known for its medium to deep blue colour and strong saturation. Fancy coloured sapphires in various colours are also available. In the United States, blue sapphire tends to be the most popular and most affordable of the three major precious gemstones (emerald, ruby and sapphire).
  • Turquoise is found in only a few places on earth, and the world’s largest turquoise producing region is the southwest United States. Turquoise is prized for its attractive colour, most often an intense medium blue or a greenish blue, and its ancient heritage. Turquoise is used in a great variety of jewellery styles. It is perhaps most closely associated with southwest and Native American jewellery, but it is also used in many sleek, modern styles. Some turquoise contains a matrix of dark brown markings, which provides an interesting contrast to the gemstone’s bright blue colour.

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.[11]

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, an example is thecubic zirconia, used in place of the diamond.

Characteristics and classification

The traditional classification in the West, which goes back to the Ancient Greeks, begins with a distinction between precious and semi-precious stones; similar distinctions are made in other cultures. In modern usage the precious stones are ruby, sapphire and emerald, with all other gemstones being semi-precious.[3] This distinction is unscientific and reflects the rarity of the respective stones in ancient times, as well as their quality: all are translucent with fine color in their purest forms, except for the colorless diamond, and very hard,[4] with hardnesses of 8-10 on the Mohs scale. Other stones are classified by their color, translucency and hardness. The traditional distinction does not necessarily reflect modern values, for example, while garnets are relatively inexpensive, a green garnet calledTsavorite, can be far more valuable than a mid-quality emerald.[5] Another unscientific term for semi-precious gemstones used in art history and archaeology ishardstone. Use of the terms ‘precious’ and ‘semi-precious’ in a commercial context is, arguably, misleading in that it deceptively implies certain stones are intrinsically more valuable than others, which is not the case.

In modern times gemstones are identified by gemologists, who describe gems and their characteristics using technical terminology specific to the field of gemology. The first characteristic a gemologist uses to identify a gemstone is its chemical composition. For example, diamonds are made of carbon (C) and rubies ofaluminium oxide (Al2O3). Next, many gems are crystals which are classified by their crystal system such as cubic or trigonal or monoclinic. Another term used ishabit, the form the gem is usually found in. For example diamonds, which have a cubic crystal system, are often found as octahedrons.

Gemstones are classified into different groupsspecies, and varieties. For example, ruby is the red variety of the species corundum, while any other color of corundum is considered sapphire. Emerald (green), aquamarine (blue), red beryl (red), goshenite (colorless), heliodor (yellow), and morganite (pink) are all varieties of the mineral species beryl.

Gems are characterized in terms of refractive index, dispersion, specific gravity, hardness, cleavage, fracture, and luster. They may exhibit pleochroism or double refraction. They may have luminescence and a distinctive absorption spectrum.

Material or flaws within a stone may be present as inclusions.

Gemstones may also be classified in terms of their “water”. This is a recognized grading of the gem’s luster and/or transparency and/or “brilliance”.[6] Very transparent gems are considered “first water”, while “second” or “third water” gems are those of a lesser transparency.

In the last two decades there has been a proliferation of certification for gemstones. There are a number of laboratories which grade and provide reports on diamonds.

  • International Gemological Institute (IGI), independent laboratory for grading and evaluation of diamonds, jewellery and colored stones.
  • Gemological Institute of America (GIA), the main provider of education services and diamond grading reports
  • Hoge Raad voor Diamant (HRD Antwerp), The Diamond High Council, Belgium is one of Europe’s oldest laboratories. It’s main stakeholder is the Antwerp World Diamond Centre.
  • American Gemological Society (AGS) is not as widely recognized nor as old as the GIA.
  • American Gem Trade Laboratory which is part of the American Gem Trade Association (AGTA) a trade organization of jewelers and dealers of colored stones.
  • American Gemological Laboratories (AGL) which was sold by “Collector’s Universe” a NASDAQ listed company which specializes in certification of collectables such as coins and stamps. It is now owned by Christopher P. Smith, who was awarded the Antonio C. Bonanno Award for Excellence in Gemology in 2009
  • European Gemological Laboratory (EGL) founded in 1974 by Guy Margel in Belgium.
  • Gemmological Association of All Japan (GAAJ-ZENHOKYO), Zenhokyo, Japan, active in gemological research
  • Gemmological Institute of Thailand (GIT) is closely related to Chulalongkorn University
  • Gemmology Institute of Southern Africa, Africa’s premium gem laboratory.
  • Asian Institute of Gemmological Sciences (AIGS), the oldest gemological institute in South East Asia, involved in gemological education and gem testing
  • Swiss Gemmological Institute (SSEF), founded by Prof. Henry Hänni, focusing on colored gemstones and the identification of natural pearls
  • Gübelin Gem Lab, the traditional Swiss lab founded by the famous Dr. Eduard Gübelin. Their reports are widely considered as the ultimate judgement on high-end pearls, colored gemstones and diamonds

Each laboratory has its own methodology to evaluate gemstones. Consequently a stone can be called “pink” by one lab while another lab calls it “Padparadscha”. One lab can conclude a stone is untreated, while another lab concludes that it is heat treated. To minimise such differences, seven of the most respected labs, i.e. AGTA-GTL (New York), CISGEM (Milano), GAAJ-ZENHOKYO (Tokyo), GIA (Carlsbad), GIT (Bangkok), Gübelin (Lucerne) and SSEF (Basel), have established the Laboratory Manual Harmonisation Committee (LMHC), aiming at the standardization of wording on reports and certain analytical methods and interpretation of results. Country of origin has sometimes been difficult to find agreement on due to the constant discovery of new locations. Moreover determining a “country of origin” is much more difficult than determining other aspects of a gem (such as cut, clarity etc.).[13]

Gem dealers are aware of the differences between gem laboratories and will make use of the discrepancies to obtain the best possible certificate.[12]

From Wikipedia, the free encyclopedia

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