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Buyers Guide

  
   

THE WORLD OF GEMSTONES

  
 
Natural gemstones are found in nature. Laboratory-created stones, as the name implies, are made in a laboratory. These stones, which also are referred to as laboratory-grown, manufacturer-created, or synthetic, have essentially the same chemical, physical, optical, and visual properties as natural gemstones. Laboratory- created stones do not have the rarity or value of natural colored gemstones. By contrast, imitation stones look like natural stones in appearance only, and may be a manmade or natural stone. Laboratory-created and imitation stones should be clearly identified as such.

Gemstones may be measured by weight, size, or both. The basic unit for weighing gemstones is the carat, which is equal to one-fifth (1/5th) of a gram. Carats are divided into 100 units, called points. For example, a half-carat gemstone would weigh .50 carats or 50 points. When gemstones are measured by dimensions, the size is expressed in millimeters (for example, 7x5 millimeters).

Gemstone treatments or enhancements refer to the way some gems are treated to improve their appearance or durability, or even change their color. Many gemstones are treated in some way. The effects of some treatments may lessen or change over time and some treated stones may require special care. Some enhancements also affect the value of a stone, when measured against a comparable untreated stone. Treatments and/or enhancements should always be disclosed by the seller.

  

 

  

ABOUT PEARLS

  

Natural pearls are found in oysters and other mollusks. Cultured pearls also are grown in mollusks, but with human intervention; that is, an irritant introduced into the shells causes a pearl to grow. Imitation pearls are man-made with glass, plastic, or organic materials.

Because natural pearls are very rare, most pearls used in jewelry are either cultured or imitation pearls. Fine quality cultured pearls, because they are harvested from oysters or mollusks, are more expensive than imitation pearls. A cultured pearl's value is largely based on its size, usually stated in millimeters, and the quality of its nacre coating, which gives it luster. The pearls color, blemish, type, and shape are also considered.

 

 
 

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