Gemstones - Quality and the Four C's
Within each gemstone variety, quality dramatically affects price: a gem can sell for $100 or $2,000,000. When buying a gemstone - buy the best quality, most experts recommend. Choose a smaller stone of higher quality over a larger stone of lower quality, or buy a higher quality gem from an unusual variety if your budget is too small.
Well-known gemstones like rubies, emeralds and sapphires - which have been known for centuries - are more valuable than more recently discovered gemstones which are also beautiful and rare. You may be surprised how beautiful and affordable garnets, tourmalines, tanzanites, and other exotic gemstones can be.
Value factors: Color, Clarity, Cut and Carat Weight
Gemstone quality and value are evaluated according to the "four Cs": color, clarity, cut, and carat weight.
Color is the 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.
The next most important factor affecting value is clarity, with clear transparent gemstones with no visible flaws being the most valued. Some gemstone varieties, notably emerald and red tourmaline, are very rare without inclusions of some kind so the price structure takes this into account.
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 cat's-eye chrysoberyl and the star in star sapphire. Inclusions can also be a birthmark, telling us where a particular gemstone was mined.
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.
Gemstones are generally sold by weight, and not by size. The price will be per carat, which is one-fifth of a gram. Some gems are heavier than others so the same weight stone may be a different size! The carat weight also affects the price: large gemstones are more rare, so the price per carat is higher.
In general, gemstone pricing within each variety follows common sense: the more beautiful the gemstone, with the final visual effect of all the quality factors, the more valuable it is. Don't be afraid to choose what looks best to you!