[P599]Precious & Semi Precious Stones

Gemstones are of two types ? precious stones and semi-precious stones. A gemstone is nothing more than a small piece of precious mineral that is polished to be used in jewelry such as necklaces, bracelets and rings.
Most gemstones are rock hard but there are some soft minerals that are used in jewelry due to their gloss and sparkle. Most jewelry makers predominantly recognize only five gemstones as precious ? Diamond, Ruby, Sapphire, Emerald and Amethyst.
There is however a large number of Semi-precious stones like Agate, Alexandrite, Aquamarine, Garnet, Topaz, Turquoise, Opal, Coral, Catseye, Zircon, Jade etc.
Gemstones are more than just glittering, colored stones. It is believed that most of them have certain special effects and psychic powers and capable of mitigating life's misfortunes when worn as jewelry. Most gems also have therapeutic values.
Gems play a pivotal role in astrology. Each of the planets is represented by a particular stone as detailed below:
Sun/Ruby; Moon/Pearl; Mars/Coral; Mercury/Emerald; Jupiter/Topaz; Venus/Diamond; Saturn/Sapphire. The two nodes Rahu and Kethu are represented by Zircon and Catseye respectively.
There are certain stones that are supposed to produce evil effects and they should be scrupulously avoided. The precious stones we wear should be free from all impurities and qualified gemologists will be able to easily distinguish the pure stones from the impure ones. There are certain artificial stones which are seemingly attractive and glittering but will not be able to produce any beneficial effects.
A few gemstones are straightaway used as gems in the crystal or in any other form in which they are originally found. Most of the other stones are cut and polished for use as gemstones.
There are stones which are cut smooth and as dome shaped stones and they are called cabochons. There are stones which are cut with a faceting machines at regular intervals and at exact angles. These are called facets.
Stones which are opaque such as opal and turquoise. are commonly cut as cabochons. Grinding wheels and polishing agents are used to grind, shape and polish these smooth dome shape of the stones.
Gems which are transparent are usually faceted, a method which bring out the optical properties of the stone's interior by maximizing reflected light which is perceived by the as sparkling quality
Color is the most obvious and attractive feature of gemstones. A colored gemstone is sought after by many especially for its great charm, rarity or aesthetics. Although color plays a very important role in determining the value of a gemstone, many other factors influence its price such as market supply, rarity and popularity of a stone.
The same original material can display different colors. For example ruby and sapphire have identical chemical composition but exhibit different colors. Even the same gemstone occurs in many different colors. For example, sapphires show different shades of blue and pink and fancy sapphires exhibit a whole range of other colors from yellow to orange-pink.
Gemstones are often treated to enrich the color and enhance the clarity of the stone. Depending on the type and extent of treatment, they can add to the luster of the stone.
Heat treatment can largely improve the color and clarity of the gemstone. Both the lighter and the darker blue shades of Topaz are radiated to change the color from white to blue. Most greened quartz is also irradiated to achieve the yellow-green color. Emeralds containing natural fissures are sometimes filled with wax or oil to disguise them. Turquoise is also commonly treated in a similar fashion. Fracture filling has been in use with different gemstones such as diamonds, emeralds and sapphires thus dramatically improving the appearance.