Buying Diamond Jewelry

The Heart of the Matter

If you're planning a gift of diamond jewelry for your sweetheart, take some time to learn the terms used in the industry. Start with the basics. Carats and karats. What's the difference? Simply put, a carat is a unit of weight for gemstones, including diamonds; a karat is a unit for measuring the purity of gold.

When you're buying a diamond, consider four criteria, often referred to as "the 4C's" - cut, color, clarity and carat weight. Each factor affects the price.

Cut not only refers to the shape of the diamond, but also to the size, angle, uniformity and polish of the facets.

Color is sometimes "graded" on a scale. However, scales are not uniform: a "D" may be the best color for one scale, but not for another. Make sure you know how a particular scale and grade represents the color of the diamond you're considering.

Clarity refers to the presence or absence of internal flaws, called inclusions, that occur naturally within the stone, or to external blemishes, such as scratches or chips. A diamond can be described as "flawless" only if it has no visible surface cracks or other imperfections when viewed under 10-power magnification by a skilled diamond grader.

Carat weight may be described in decimal or fractional parts of a carat. If the weight is given in decimal parts of a carat, the figure should be accurate to the last decimal place. For example, ".30 carat" could represent a diamond that weighs between .295 - .304 carat. Some retailers describe diamond weight in fractions and use the fraction to represent a range of weights. For example, a diamond described as ½ carat could weigh between .47 - .54 carat. If diamond weight is stated as fractional parts of a carat, the retailer should disclose two things: that the weight is not exact, and the reasonable range of weight for each fraction or the weight tolerance being used.

Diamond Weight

Decimal Representations

If the diamond's weight is described in decimal parts of a carat, the figure should be accurate to the last decimal place. For example, ".30 carat" could represent a diamond that weighs between .295 and .304 carat. If the weight is given to only one decimal place, it should be accurate to the second decimal place: If you say a diamond weighs .5 carat, the diamond should weigh between .495 and .504 carat.

Fractional Representations

If the diamond's weight is described in fractions, the fraction may represent a range of weights. For example, a diamond described as « carat could weigh between .47 and .54 carat. If you use the fraction method, you also should disclose that the diamond weight is not exact and the reasonable range of weight for each fraction or the weight tolerance used.

Diamond Testers and Moissanite

Thermal testers used to distinguish diamonds from cubic zirconia may not accurately identify moissanite - a laboratory-created gemstone that resembles a diamond. As a result, this stone may falsely register as a diamond on your thermal detector. How can you ensure that you recognize moissanite for what it is? A newer tester can do it for you, or you may have to learn other ways to distinguish moissanite from diamonds.