Precious, brilliant and expensivewhy wouldn't diamonds be a girl's best friend? When giving the most significant gift of a lifetime, most men, and even the women who receive them, know precious little about diamonds. By the time they're old and experienced enough to know about cut, shape, grade, brilliance, color, weight, and setting, they already have the diamond of a lifetime. Crack the vocabulary, and you'll be on your way to purchasing your first diamond with confidence.

The Four Cs

Diamonds are not created equally! "The Four Cs of Diamonds" cut, clarity, color, and carat determine diamond grade. A diamond certificate accompanies each diamond and includes grades for each of the four Cs as documented by a gemologist. Learn what these terms mean to avoid that "deer in the headlights" look when the jeweler uses these terms.

Cut refers to the physical cut, not the shape of the diamond, and it affects the brilliance of the diamond. If the cut is too shallow or too deep, the refraction of the light detracts from the brilliance. Grades for cut, from best to worst, include Ideal, Premium, Very Good, Good, Fair and Poor. The Ideal grade applies exclusively to round diamonds.

Clarity measures the purity of the diamond. Most diamonds include some flaws, called inclusions. All but the rare flawless diamonds contain inclusions of varying number and size. The Clarity grade measures the purity of the diamond, the relative absence of flaws. Clarity grades the appearance under 10X magnification. Top grades include F (flawlessforget it, you'll never see this), IF (internally flawless, you'll never afford it), VVS1-VVS2 (very, very slightly flawednot we're getting a little more realistic), VS1-VS2 (very slightly flawed), and SI1-SI2 (slightly flawed). All but the VS1-VS2 and SI1-SI2 diamonds contain flaws that are invisible or barely visible under 10X magnification. Lesser grades include I1- -I3 (flawed and obvious without magnification). If price is a consideration, then invisible to the naked eye is a reasonable tradeoff.

Color actually refers to the absence of color in diamonds. The finest diamonds are colorless, which allows them to absorb and reflect more light, displaying more brilliance. White diamonds range from ice white to light yellow. Color is graded on a scale from D-Z, with D-grade diamonds being colorless and Z-grade diamonds containing the most color. Grades G-J are near colorless to the human eye, and offer the best value for the money.

Carat refers to weight. Because large diamonds are extremely rare, the price rises exponentially rather than arithmetically according to carat weight.

Each of the four Cs affects price. Once you set a budget, determine the attributes most important to you and select your diamond according to your preferences.

Learn a few more simple terms, and you're well on your way to demystifying the world of diamonds and carrying on a conversation with your jeweler that will turn the heads of less astute shoppers.

Shape also affects price, but only in terms of "shape appeal," how pleasing the shape is to the naked eye. By far, the most popular shape is the Round diamond, and it's the most expensive as well. Fancy shapes such as Emerald, Marquis, Pear, Heart, Oval, Radiant and Princess, are less expensive than Round diamonds. Side by side, fancy diamonds look larger than Round diamonds of equal carat weight. If you want something out of the ordinary, a fancy shape might be right for you.

Facets refer to the flat, polished surfaces of the diamond. The round diamond checks in at 58 facets, the most facets of all the shapes. The most important facet is the top or Table facetthe largest facet. Diamonds cut to perfection enable the facets to refract the light brilliantly.

Settings should enhance the brilliance and size of the stones, not detract from them. The range of choices is stunning, from the metal to the prong display. Even more than shape, the setting reflects your personal preference and style.

Now that you understand the clandestine vocabulary of diamonds, you can relax and have fun while selecting that one-of-a-kind, perfect diamond for you