A gemstone usually refers to a rock or mineral that is used in jewelry or as a collector's item, usually after it has been polished, cut or faceted.

Gemstones are classified through several ways. They may be grouped according to chemical composition -- for example, rubies are made of aluminum oxide and diamonds are made of carbon. If they are crystals, they may be classified using the crystal system, which divide gemstones into cubic, trigonal or monoclinic. They are also classified according to habit, which refers to the shape of the stones. It's also possible to group gemstones according to species -- for example, the mineral species beryl would include such gemstones as emerald, aquamarine, bixbite, goshenite, heliodor and morganite.

Buying a gemstone can be an absolute joy. Imagine the thrill of being surrounded by a roomful of precious gems, with colors that dazzle and captivate. Over 30 types of gem varieties have been identified, not counting those rare, singular gemstones that show up once in a while and defy category. Some of these gemstones have decorated and adorned the earliest civilizations of man, while others are recent discoveries but nonetheless as impressive as their forebears.

Emeralds are the most popular gemstones in the world and have been esteemed since ancient times. They are a dazzling green all over, alternately shiny and intense to the eye. The highest-quality emeralds are more coveted than diamonds, a little known fact. They were named from the word "esmeralde" which is Old French for "green gemstone." Their rich history dates back to the times of great ancient civilizations like the Incas and Aztecs. Its roots are buried deep in the jungles of South America where the rarest of emeralds can still be found.

The ruby is the gemstone that best represents love and vitality, passion and intensity. The ruby has long been regarded as first among gemstones, their bright red glow that conveys strength and warmth. These qualities made the ruby the most valuable gemstone for centuries, a royal favorite of emperors and kings.

Often compared to the blue sky in literature and history, sapphire has as many shades as the sky has hues. Legend has it that early man actually believed that the sky was made of one big block of sapphire and that the earth was simply a thorn on its side. Among emotions, Sapphire is associated with noble feelings of harmony, friendship, loyalty and sympathy. And since blue is the favorite color of about half the world's population, sapphire's appeal and popularity worldwide is not surprising.