The beauty, rarity, and historical mystique of gems are timeless. In addition to their amazing kaleidoscopic array of colors, they also provide an exotic range of special optical properties that borders on mesmerizing. However, before you make a purchase, it will be helpful to have a basic understanding of gemstones.
Ask different people this question and you will get different answers. From the perspective of a gemologist, a gemstone is a naturally-occurring organic or inorganic material that possesses a certain degree of beauty, rarity and durability. However, these three factors are relative and subjective to some extent. What one culture considers beautiful may be perceived differently by another. Some gems may be durable enough to survive the process of jewelry setting, but often require special care during wear to prolong their beauty.
In the broadest sense, some would say that a gemstone can be any material, natural or man-made, that can be used for personal adornment. In the case of man-made materials, rarity is not a factor. It should be noted, though, that some man-made gems are much more expensive to produce than others. Some types are also much more difficult to acquire.
Inorganic gemstones consist of minerals, mineraloids and rocks. These are created by geologic processes within the earth. Organic gemstones are the product of living organisms, past or present. Pearls, coral, amber and ivory are good examples of the latter.
Man-made gems may or may not have naturally0occurring counterparts. If a natural counterpart does exist, the gem is said to be synthetic. Synthetic ruby and sapphire are two good examples. If a man-made gem material has no natural counterpart, it falls into the category of artificial YAG (yttrium aluminum garnet) and GGG (gadolinium gallium garnet) are examples.