Opal - The Watery Gemstone

Published: 28th January 2009
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Opal jewelry comes in many forms and styles. Silver pendants , bracelets, earrings, necklaces and rings are quite popular in today's fashion jewelry. One key reason for the popularity of opal in fashion jewelry is the wide range of colors in which it is available. This stone is available in cool colors such as blues, greens, purples, as well as warmer colors like pinks, reds, yellows, and oranges. Unconventional jewelry designs provide new and exciting options to the wearer. But like all other types of jewelry, choosing the right type of opal jewelry for the right occasion requires at least some basic knowledge with regards to availability, cost, and care.

Opal is a noncrystalline form of the mineral silica which, despite its amorphous structure, displays an amazing degree of internal organization. The stone is related to its more commonly found but highly crystalline cousins quartz and agate, and is formed from amorphous "balls" or lumps" of silica rather that from ordered, naturally faceted crystals. It is formed from silica-bearing waters and can be found inside any type of rock. Throughout the world, silica gel precipitates at low temperatures to form layers or nodules of opal in fissures, veins, and cavities of volcanic and sedimentary rocks. Opal is an amorphous form of silica (SiO2.nH2O), chemically similar to quartz (SiO2), but containing 3% to 21% water within its mineral structure. Opals of gemstone quality usually contain 6% to 10% water. Because of the high percentage of water content, opal may be damaged by heat and cold. In the precious form of this stone, the silica is arranged into tiny randomly placed structures with water between them. The colors are because of the scattering and interference of light from the silica-water interfaces. They are, in many ways, similar to those you get from soap bubbles; here, the silica plays the role of soap.

Opals are found in different hues and colors such as black, red yellow and white. Several varieties are available and each variety is attractive in it own way. The different types include harlequin, common, fire, water, wood and precious opal. Black opals are the most rare and expensive opals, with a body color that can range from dark grey to black with fiery flashes of color. Precious fire opals are another alternative. They have base colors ranging from yellow to orange, and can be transparent to translucent with fiery flashes. Opal is predominantly found in Australia and is officially recognized as the national gemstone. Fire opals are mostly composed of silica acid with high water content and footprints of iron oxide that reflects the color. These are precious stones often called Mexican fire opals they look more beautiful when processed on fine jewelries such as rings and necklaces. US researchers now report that opal-like deposits have been spotted on Mars! However, don't hold your breath for "Mars Opals" to hit the fashion jewelry scene anytime in the foreseeable future!

Opals are delicate, but well worth the care. Their most significant weakness has to do with the water content. If an opal is allowed to dry, it will crack and craze. In most cases, they do not need any special care while stored. However, if you live in a very dry climate, or keep them in a dehumidified room, some precautions are necessary. Keeping them in a tight plastic bag, with a damp piece of cotton or fabric will prevent dehydration. Storing an opal in oil or glycerin is not recommended. It is unlikely to damage the opal, but it is unnecessary and requires tedious cleaning. Because of the fragility of the opal, it should be cut thickly. The stone will deteriorate in time if the cut is finer. Opal should be washed every now and then to remove the traces of perspiration or cosmetics. If your opal loses some of its shine, it can be recut or repolished by a jeweler.

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