LYCOS RETRIEVER 
Gemstones: Stones
built 292 days ago
Gemstones are often treated to enhance the color or clarity of the stone. Depending on the type and extent of treatment, they can affect the value of the stone. Some treatments are used widely because the resulting gem is stable, while others are not accepted most commonly because the gem color is unstable and may revert to the original tone.[11]
Source:
Traditionally, gemstones were classified into precious stones and semi-precious stones. Only four types of gemstones were considered precious (diamond, ruby, sapphire and emerald). Nowadays, all gems are considered "precious," although the four original "cardinal gems" are usually - but not always - the most expensive. There are over 130 species of minerals that have been cut into gems with 50 species in common use. In addition, there are a number of organic materials used as gems.
Source:
There are many other common types of treatment to enhance the beauty of colored gemstones. Emeralds are often oiled and waxed to protect them and to hide fine lines that naturally occur in the stone. Some sapphires have their blue color enhanced using diffusion, a chemical process. Certain stones are treated with radiation, again mimicking the processes of nature. All these practices are standard in the jewelry industry; in fact, enhancement is so common that good quality unenhanced stones often come with a certificate stating that fact.
Source:
There are ... many other forms of lapidary, not just cutting and polishing stones and gemstones. These include; casting, faceting, carving, jewelery, mosaics (eg. little slices of opal on potch, obsidian or another black stone and with a clear dome (glass or crystal quartz) on top. There are lapidary clubs through-out the world and in Australia there is an annual gemshow, the Gemborree which is a nation-wide lapidary competition. The largest mineral show in the world is the Tucson Gem and Mineral Society Show held annually in Arizona, USA.
Source:
Some gemstones are manufactured to imitate other gemstones. For example, cubic zirconia is a synthetic diamond simulant composed of zirconium oxide. The imitations copy the look and color of the real stone but possess neither their chemical nor physical characteristics. However, true synthetic gemstones are not necessarily imitation. For example, diamonds, ruby, sapphires and emeralds have been manufactured in labs to possess very nearly identical chemical and physical characteristics to the naturally occurring variety. Synthetic corundums, including ruby and sapphire, are very common and they cost only a fraction of the natural stones.
Source:
The geological processes create an astonishing variety of beautiful gemstones. Only a few are ready for jewelry in their natural state, so, many companies treat their stones to enhance their color and brilliance or stabilize their chemical composition, making more high-quality gems available to the public. It has been estimated that 80-percent of all gemstones are treated in some way before reaching the retailer. Every jewelry description at Overstock.com includes gemstone treatment codes; you can visit Overstock.com's Gemstone Treatment Guide and know exactly what you're getting before you buy.
Source:
MORE ABOUT
Stones