    
| Quality And Value Of Gemstones Today Becoming an educated consumer is not such an easy matter when dealing with all the variables related to the purchase of a gemstone. Today, the quality and value of a gemstone is determined by a combination of what are called the ""Four C's"": Clarity (degree of flawlessness), Color, Cut and Carat weight.
Clarity is the degree of flawlessness. As a rule, a clear transparent gemstones with no visible flaws is the most valued. GIA (Gemological Institute of America) classifies colored gems clarity of three types:
Type 1 gemstones, "virtually inclusion-free" such as aquamarine, topaz, green tourmaline, tanzanite, citrine.
Type 2 gemstones, "usually included" such as rubies, sapphires, garnets, peridots, amethysts, zircons.
Type 3 gemstones, almost "always included", such as emeralds and red tourmalines.
Some gemstones are valued for their inclusions! Phenomenal gemstones owe their stars and eyes to inclusions. Tiny inclusions reflecting back light put the eye in the cat's eye and the star in the star sapphire. Inclusions can also be a birthmark, telling us where a particular gemstone was mined.
Color is another key factor. A common misperception in judging gems is people assume that the darker the color, the better the stone. That isn't true: color can be too dark, like some sapphires that look more black than blue. If a gem's color is too dark, it is subdued and lifeless. A much better rule of thumb is the brighter and more rich and vivid the color, the better. In general, within each gemstone variety, a clear, medium-tone, very intense and saturated primary color is the most preferred. Muted colors or colors between hues, which you might find very attractive, are usually less expensive. Look at the color in different kinds of light. Sometimes, in daylight, a gem shows one color and in artificial light another one. This color change gems are usually very attractive and in most case expensive (ALEXANDRITE is the most known example, but sapphires, garnets, spinels can also change color).
A good Cut is something that may not cost more but can add or subtract a lot of beauty. A well-cut faceted gemstone reflects light back evenly across its surface area when held face up. If the stone is too deep and narrow, areas will be dark. If it is too shallow and wide, parts of the stone will be washed out and lifeless. The best way to judge cut is to look at similar gemstones next to each other.
The most common cuts are showed here:
The weight of a gemstone is measured in Carats and points. There are 100 points in one carat, which equals to one-fifth of a gram. As a rule, the price increases per carat as we go from smaller to larger stones, since the larger stones are more limited in supply. However, the price does not increase proportionately - there are disproportionate jumps. And the larger the stone (all else being equal in terms of overall quality), the more disproportionate the increase in cost per carat may be.
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