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Sunday, May 30, 2010

Vegas preview: Betting on silver

source : nationaljewelernetwork.com
By Catherine Dayrit
May 26, 2010

sterling silver bracelet
In Las Vegas, Calgaro will be offering its "Jealousy Collection" bracelets, evocative of fabric and crafted in sterling silver with a patented colorized silver fabrication; suggested retail price is $795. (818) 319-4200 or CalgaroUSA.com

With Las Vegas Market Week fast approaching, retail jewelers are spending a last couple of days examining their inventory and fine-tuning their shopping lists.

While fill-in staples such as bridal, diamond solitaire pendants and anniversary bands are sure to make the cut, buyers are likely to hone in on two other specific merchandise categories: the high-end couture sector and the entry-level price-point arena.

Recent reports in the press, combined with market surveys, point out that activity has been returning at the very high end of the market. It's good news, but still, that is just the very tip-top of the market and many consumers remain cautious about spending. ...

Sunday, May 23, 2010

Pearl Jewelry

pearl earringspearl jewelrypearl jewelryblack pearl ringblack pearl ringpearl jewelryblack pearl ringpearl jewelrypearl jewelrypearl ring


source : wikipedia

A pearl is a hard object produced within the soft tissue (specifically the mantle) of a living shelled mollusk. Just like the shell of a mollusk, a pearl is made up of calcium carbonate in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes of pearls (baroque pearls) occur. The finest quality natural pearls have been highly valued as gemstones and objects of beauty for many centuries, and because of this, the word pearl has become a metaphor for something very rare, fine, admirable, and valuable.

Valuable pearls occur in the wild, but they are very rare. Cultured or farmed pearls from pearl oysters make up the majority of those that are currently sold. Pearls from the sea are valued more highly than freshwater pearls. Imitation or fake pearls are also widely sold in inexpensive jewelry, but the quality of their iridescence is usually very poor - and generally speaking, artificial pearls are easily distinguished from genuine pearls. Pearls have been harvested and cultivated primarily for use in jewelry, but in the past they were also stitched onto lavish clothing. Pearls have also been crushed and used in cosmetics, medicines, or in paint formulations.

Pearls that are considered to be of gemstone quality are almost always nacreous and iridescent, like the interior of the shell that produces them. However, almost all species of shelled mollusks are capable of producing pearls (formerly referred to as "calcareous concretions" by some sources) of lesser shine or less spherical shape. Although these may also be legitimately referred to as "pearls" by gemological labs and also under U.S. Federal Trade Commission rules, and are formed in the same way, most of them have no value, except as curios.


Almost any shelled mollusk can, by natural processes, produce some kind of "pearl" when an irritating microscopic object becomes trapped within the mollusk's mantle folds, but the great majority of these "pearls" are not valued as gemstones. Nacreous pearls, the best-known and most commercially-significant pearls, are primarily produced by two groups of molluscan bivalves or clams. A nacreous pearl is made from layers of nacre, by the same living process as is used in the secretion of the mother of pearl which lines the shell.

A "natural pearl" is one that forms without any human intervention at all, in the wild, and is very rare. Many hundreds of pearl oysters or pearl mussels have to be gathered and opened, and thus killed, in order to find even one wild pearl, and for many centuries that was the only way pearls were obtained. This was the main reason why pearls fetched such extraordinary prices in the past. A cultured pearl, on the other hand, is one that has been formed with human intervention on a pearl farm.

One family of nacreous pearl bivalves, the pearl oysters, lives in the sea while the other, very different group of bivalves live in freshwater; these are the river mussels such as the freshwater pearl mussel. Saltwater pearls can grow in several species of marine pearl oysters in the family Pteriidae. Freshwater pearls grow within certain (but by no means all) species of freshwater mussels in the order Unionida, the families Unionidae and Margaritiferidae.

A black pearl and a shell of the black-lipped pearl oyster

A pearl being extracted from an akoya pearl oyster.

Value of a natural pearl

Quality natural pearls are very rare jewels. The actual value of a natural pearl is determined in the same way as it would be for other "precious" gems. The valuation factors include size, shape, quality of surface, orient and luster.

Single natural pearls are often sold as a collector's item, or set as centerpieces in unique jewelry. Very few matched strands of natural pearls exist, and those that do often sell for hundreds of thousands of dollars. (In 1917, jeweler Pierre Cartier purchased the Fifth Avenue mansion that is now the New York Cartier store for US$100 cash and a double strand of matched natural pearls valued at the time at US$1 million.)

Keshi pearls, although they often occur by chance, are not considered natural pearls. They are a byproduct of the culturing process, and hence do not happen without human intervention. These pearls are quite small: typically a few millimeters in size. Keshi pearls are produced by many different types of marine mollusks and freshwater mussels in China. Today many "keshi" pearls are actually intentional, with post-harvest shells returned to the water to regenerate a pearl in the existing pearl sac.

source : http://en.wikipedia.org/wiki/Pearl

Opal Jewelry

opal jewelry photoopal jewelry photoopal jewelry photoopal jewelry photoopal jewelry photo

Opal : as a mineral

source : wikipedia.org

Opal is a mineraloid gel which is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marl and basalt. The word opal comes from the Latin opalus, by Greek ὀπάλλιος opallios.

The water content is usually between three and ten percent, but can be as high as twenty percent. Opal ranges from clear through white, gray, red, orange, yellow, green, blue, magenta, rose, pink, slate, olive, brown, and black. Of these hues, the reds against black are the most rare, whereas white and greens are the most common. These color variations are a function of growth size into the red and infrared wavelengths. Opal is Australia's national gemstone.

Precious opal

Precious opal shows a variable interplay of internal colors and even though it is a mineraloid, it does have an internal structure. At micro scales precious opal is composed of silica spheres some 150 to 300 nm in diameter in a hexagonal or cubic close-packed lattice. These ordered silica spheres produce the internal colors by causing the interference and diffraction of light passing through the microstructure of the opal.It is the regularity of the sizes and the packing of these spheres that determines the quality of precious opal. Where the distance between the regularly packed planes of spheres is approximately half the wavelength of a component of visible light, the light of that wavelength may be subject to diffraction from the grating created by the stacked planes. The spacing between the planes and the orientation of planes with respect to the incident light determines the colors observed. The process can be described by Bragg's Law of diffraction.

Visible light of diffracted wavelengths cannot pass through large thicknesses of the opal. This is the basis of the optical band gap in a photonic crystal, of which opal is the best known natural example. In addition, microfractures may be filled with secondary silica and form thin lamellae inside the opal during solidification. The term opalescence is commonly and erroneously used to describe this unique and beautiful phenomenon, which is correctly termed play of color. Contrarily, opalescence is correctly applied to the milky, turbid appearance of common or potch opal. Potch does not show a play of color.

The veins of opal displaying the play of color are often quite thin, and this has given rise to unusual methods of preparing the stone as a gem. An opal doublet is a thin layer of opal, backed by a swart mineral such as ironstone, basalt, or obsidian. The darker backing emphasizes the play of color, and results in a more attractive display than a lighter potch.

Combined with modern techniques of polishing, doublet opal produces similar effect of black or boulder opals at a mere fraction of the price. Doublet opal also has the added benefit of having genuine opal as the top visible and touchable layer, unlike triplet opals.

The triplet-cut opal backs the colored material with a dark backing, and then has a domed cap of clear quartz or plastic on top, which takes a high polish and acts as a protective layer for the relatively fragile opal. The top layer also acts as a magnifier, to emphasize the play of color of the opal beneath, which is often of lower quality. Triplet opals therefore have a more artificial appearance, and are not classed as precious opal.

Precious opal consists of spheres of silica of fairly regular size, packed into close-packed planes which are stacked together with characteristic dimensions of several hundred nm.

Common opal

Besides the gemstone varieties that show a play of color, there are other kinds of common opal such as the milk opal, milky bluish to greenish (which can sometimes be of gemstone quality), resin opal which is honey-yellow with a resinous luster, wood opal which is caused by the replacement of the organic material in wood with opal, menilite which is brown or grey, hyalite is a colorless glass-clear opal sometimes called Muller's Glass, geyserite, also called siliceous sinter, deposited around hot springs or geysers and diatomite or diatomaceous earth, the accumulations of diatom shells or tests.

Other varieties of opal

Polished opal from Yowah, Queensland, AustraliaFire opals are transparent to translucent opals with warm body colors yellow, orange, orange-yellow or red and they do not usually show any play-of-color, although occasionally a stone will exhibit bright green flashes. The most famous source of fire opals is the state of Querétaro in Mexico and these opals are commonly called Mexican fire opals.

Peruvian opal (also called blue opal) is a semi-opaque to opaque blue-green stone found in Peru which is often cut to include the matrix in the more opaque stones. It does not display pleochroism.

Sources of opal

Australia produces around 97% of the world's opal. 90% is called ‘light opal’ or white and crystal opal. White makes up 60% of the opal productions but cannot be found in all of the opal fields. Crystal opal or pure hydrated silica makes up 30% of the opal produced, 8% is black and only 2% is boulder opal.

The town of Coober Pedy in South Australia is a major source of opal. Andamooka in South Australia is also a major producer of matrix opal, crystal opal, and black opal. Another Australian town, Lightning Ridge in New South Wales, is the main source of black opal, opal containing a predominantly dark background (dark-gray to blue-black displaying the play of color). Boulder opal consists of concretions and fracture fillings in a dark siliceous ironstone matrix. It is found sporadically in western Queensland, from Kynuna in the north, to Yowah and Koroit in the south.
The Virgin Valley opal fields of Humboldt County in northern Nevada produce a wide variety of precious black, crystal, white, fire, and lemon opal. The black fire opal is the official gemstone of Nevada. Most of the precious opal is partial wood replacement. Miocene age opalised teeth, bones, fish, and a snake head have been found. Some of the opal has high water content and may desiccate and crack when dried. The largest black opal in the Smithsonian Institution comes from the Royal Peacock opal mine in the Virgin Valley.

Another source of white base opal or creamy opal in the United States is Spencer, Idaho. Spencer has an open pit mine that you can visit for a fee, about 4 times a year. One business in Spencer also brings material down from the mine site to their store, so that would be opal miners can dig for their own opal, again for a nominal fee. A high percentage of the opal found there occurs in thin layers. As a result, most of the production goes into the making of doublets and triplets.

Other significant deposits of precious opal around the world can be found in the Czech Republic, Slovakia, Hungary, Turkey, Indonesia, Brazil (Pedro II a city in the state of Piauí), Honduras, Guatemala, Nicaragua and Ethiopia.

In late 2008, NASA announced that it had discovered opal deposits on Mars.

Historical superstitions

In the Middle Ages, opal was considered a stone that could provide great luck because it was believed to possess all the virtues of each gemstone whose color was represented in the color spectrum of the opal. It was also said to confer the power of invisibility if wrapped in a fresh bay leaf and held in the hand.Following the publication of Sir Walter Scott's Anne of Geierstein in 1829, however, opal acquired a less auspicious reputation. In Scott's novel, the Baroness of Arnheim wears an opal talisman with supernatural powers. When a drop of holy water falls on the talisman, the opal turns into a colorless stone and the Baroness dies soon thereafter. Due to the popularity of Scott's novel, people began to associate opals with bad luck and death.Even as recently as the beginning of the 20th century, it was believed that when a Russian saw an opal among other goods offered for sale, he or she should not buy anything more since the opal was believed to embody the evil eye.

Opal is considered the birthstone for people born in October or under the sign of Libra and the star stone for people born under Scorpio.

Sunday, May 16, 2010

Jewels Shine at Auction

source : nytimes.com

"Gems and jewels have been doing brilliantly at auction for months, as if bidders had never been told that there is a recession," Souren Melikian writes.A late 18th-century pair of ear clips with spinels and diamonds, cataloged as "the property of a German Princely and Liechtenstein Ruling Family," almost quadrupled the high estimate at $105,000 at Sotheby's Geneva auction.On Dec. 10, when the mood in London was at an all-time low, Christie's sold the most expensive jewel ever. The 35.56-carat blue diamond rose to $24.31 million, or to be strictly accurate, £16.39 million, to Laurence Graff of London.The gem's history goes back to the 17th century, when Philip IV of Spain gave it to his daughter Margaret Theresa on her betrothal to Leopold I, the ruler of the "Roman Germanic Empire." Later, it belonged to the Princes of Wittelsbach in Bavaria. The stone was cut by Sa'ida-ye Gilani, the Iranian poet, calligrapher and jeweler employed at the Moghul court by the emperor Jahangir (who reigned from 1605-1627), thus multiplying its potential value manyfold. However, the catalog did not mention this, since it was not known at the time of the sale.Five months later, another extraordinary price within its range was realized at Sotheby's in Geneva. A fancy blue diamond, a 7.03-carat gem, brought in $9.48 million, just over $1.34 million a carat, making the diamond the most expensive stone per carat ever sold in any category.Where aristocratic provenance could be established, jewels soared sky-high. A diadem and necklace made by Cartier in 1912 for Olga Princess Paley, Countess of Hohenfelsen, both doubled their high estimates. The diadem (described as an "aigrette tiara") set with rose-cut diamonds and two aquamarines, brought $512,014.The necklace, designed in the same heavily ornate style, cost an equally breathtaking $392,700.
At Christie's late spring London sale of jewelry on June 10, signed jewels set with good quality stones sold like hot cakes regardless of style or period.

A necklace made from oval gold links joined by diamond-set clasps and signed Cartier Paris excited bidders, who sent it climbing to $42,750, more than triple the estimate.
Christie's "superb antique diamond brooch" was an unusual composite piece. Made up from magnificent 18th-century pear-shaped diamond drops hanging from an inverted lotus chalice, it exceeded the high estimate as a private collector from Britain footed the $374,824 bill.
In its own modest line, an Art Deco travel clock of spinach-green jade, its dial framed by a gold chain motif set off by black enamel, provided evidence of the private buyers' sunny disposition, as it brought $14,260, substantially more than the high estimate.

source : nytimes.com

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