When buying diamond jewelry, adhere to the Four Cs of diamond quality. Be especially mindful of cut and color.

When you look at the stone, it should have an even brilliance, with no parts looking shadowed or dark. Experts warn that improperly cut diamonds, especially pear, oval and marquise shapes, can give a viewer an undesired "bow-tie" shadow effect when looking at it.

Also on the matter of cut, be sure the facets are of an even and symmetrical size and well-polished. The outline of the stone must be even and well-defined.

In terms of color, unless you are buying a fancy colored diamond, you'll want your stone to be as close to totally colorless as possible. It's that colorlessness that gives the stone the most reflective and refractive properties--in other words, what gives a diamond its sparkle.

Color

When buying a ruby, sapphire, emerald or any other colored gemstone, look for rich color, translucency and brilliance. Don't make the mistake of thinking a very dark-colored stone is more valuable than a lighter one. Your best rule of thumb is to look for vibrant color rather than deep color.

Just as clarity is important in a diamond, transparency and translucency are essential in colored gemstones. Because they are formed in nature, most gemstones do have some inclusions but many are invisible to the naked eye. Some gems, such as emeralds, tourmalines, peridots and rubellites, have more inclusions than other stones, but this is not always considered a negative factor if their color is strong

Styling Sense

When buying a piece of gemstone jewelry, let your eye be the judge. Look for harmony and balance. For example, in a gemstone ring the stone and the ring shank should be in proportion. To have a very large stone balanced on a thin ring would look silly. Likewise, a very thick band and heavy setting for a small stone is not desirable.

In fact, many of the best-designed pieces of jewelry use several different sizes and shapes of stones and different setting techniques to achieve a unique look. For example, an engagement ring may have a round, brilliant center stone held in place with six prongs, widely known as a "Tiffany" setting. The center stone might be bordered on two sides by rows of diamond baguettes (long, rectangular cut diamonds) in a channel setting, where the stones touch each other at the sides and are held in place by two railroad tracks of metal. Or, the center stone could be raised above a surface covered with tiny diamonds, known as diamond pave.

Attention to Detail

With a prong setting, be sure the prongs are balanced evenly around the stone and hold the stone securely. If stones are set in a bezel--a sort of gold picture frame of metal around the stone--be sure the bezel is straight and uniform and the stone is not moving within the setting.

In channel or invisible settings, where many stones are set tightly together with no metal showing, the stones should all be the exact size, shape and color. The facets should all line up and no one stone should be more prominent than another.

In pave, where tiny stones are set into a gold surface and the gold is pushed up around each stone using a hand-held tool, you should see nothing but a sparkling surface of diamonds. If the surface is uneven, or one stone is higher or lower than the ones around it, it's not good workmanship. Most times, white diamonds will be pave set in platinum or white gold, but pave can be done in yellow or pink gold as well.

Finally, to judge the quality of any piece of jewelry, turn it over. The back (or inside of a ring) should be just as beautiful as the front, polished and beveled nicely, not rough and unfinished-looking. If you have a piece with several stones set closely together, the metal should be cut away in square or honeycomb patterns at the back, (known as gallery work), allowing the maximum amount of light to shine through.

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