Wednesday, February 15, 2006

Diamond Basic Faq

Q. What is a diamond?

A. A diamond is a mineral composed essentially of carbon crystallized at extremely high temperatures and pressures; in nature, diamonds form 150 to 200 kilometers (93 to 124 miles) or more below the earth's surface. Diamond is the hardest of all known natural substances (10 on the Mohs scale); its refractive index is 2.417, dispersion 0.044, specific gravity 3.52, and its luster is adamantine. Diamond forms in the cubic, or isometric, crystal system, has four directions of perfect octahedral cleavage, and shows a step-like fracture surface. Its color ranges from colorless to yellow, brown, gray, orange, green, blue, white, black, purple, pink, and, extremely rarely, red. Transparent and near-colorless in a desirable color, diamond is a highly valued gemstone; poorly colored or heavily included single crystals are used for a wide variety of industrial purposes; polycrystalline material is crushed and used as an abrasive powder.

Every diamond is different, incorporating a complex constellation of factors that determine the rarity of each stone. Although gemologists train for years to master the art and science of diamond appraisal, with a little basic instruction, anyone can learn how to read an appraisal and compare the grades of different stones.

Each diamond is as unique as the person who owns it. Just as a diamond reflects the color of the light it bears, it should also reflect the personality of the individual who wears it. Here lies the art of selecting a diamond, for yourself or as a gift.

Your knowledge of yourself, if you are buying for yourself, or your knowledge of a loved one, if the diamond is a gift, is expressed in your selection. Through your choice of a diamond, you are making a public statement about the loved one--and about your relationship--and that statement is repeated every time the diamond is worn.

This is why, for many women, there is such mystique in diamond jewelry gifts, and why, for many men, there is such uncertainty in its selection. What is important in the selection of a diamond has little to do with the cost of the jewelry and much to do with the richness of the relationship.

Truly flawless diamonds are very rare, and very expensive, so you will seldom face the task of selecting a perfect diamond. It is a fairly simple matter to find beautiful diamonds with no flaws visible to the naked eye and buy them at reasonable prices.

Diamonds are graded using a system that judges the stone on its color, clarity, cut and carat weight - commonly known as the "four C's." Diamonds of uncommonly high quality and size are often sold as "certified diamonds" and come with a certificate that proves the stone's value. Even non-certified diamonds, however, should be evaluated using the four C's to help determine cost.

In this section, you will learn what each of the C's means and how it affects the value of the diamond. Although it takes a trained eye to actually see the qualities described here, knowing what they mean can help you make a good choice in selecting your diamond.

Q. What are the “Four Cs” of diamond quality?

A. The key to a diamond’s value is its rarity, and no two diamonds are alike. Rarity is determined by a diamond's unique characteristics as measured by the Four Cs: Cut, Color, Clarity and Carat Weight. Using these criteria, a small diamond of exceptional quality will likely be more valuable than a larger diamond of lower quality.


Q. What is a “Carat”?

A. Diamonds are weighed using metric carats. A carat weighs about the same as a small paper clip. Just as a dollar is divided into 100 pennies, a carat is divided into 100 “points.” This means that a diamond of 50 points weighs 0.50 carats. But two diamonds of equal weight can have very different values depending on their clarity, color and cut.

The weight of a diamond is generally given in carats. One carat equals 0.2 grams. The weight of small diamonds is frequently expressed in points, with one point equaling 0.01 carats.

Carat is the term used to describe the weight of any gemstone, including diamonds. Although the definition of a carat has changed over time, since 1913 the international standard has been 200 milligrams, or 1/5 of a gram. Often, jewelers describe carats in 1/4 increments.

In jewelry pieces with more than one diamond, the carats may be described in terms of total carat weight (TW). This is the combined total weight of all the stones in the piece.

Diamonds can range in size from a fraction of a carat to several carats. Given the rarity of large stones, however, the price increases rapidly with size; therefore, a single 2-carat diamond will cost much more than two 1-carat diamonds. Very large diamonds with good color and clarity are very rare.

Expect to pay a premium for stones that are above a full carat weight. For example, a .95 carat diamond will cost a bit more than a .90 carat stone, but a 1-carat stone will cost significantly more than a .95 carat stone.

Because round brilliant cuts follow exact standards, you can make a good estimate of the carat weight of the stone based on the stone's diameter. The following chart compares the relative sizes of stones and describes how much a round brilliant diamond of a certain size is likely to weigh. This method doesn't work as well for other cuts or shapes, though, since some are thicker or thinner than others; nor does this chart apply to colored gemstones, which have a different density from diamonds.

As diamonds increase in weight, their size becomes less predictable. Diamonds with a shallow cut can have a greater diameter than a deep cut with the same weight. So if size is important to you, focus on diamond measurements as opposed to carat weight. Diamonds that look big for their weight may have reduced brilliance and fire. An increase in carat weight does not produce the same increase in millimeter diameter. For example, there is a 25% increase in carat weight from 1.00 carats to 1.25 carats but less than 8% increase in diameter (6.5 to 7.0 mm).

Look for diamonds that have a diameter measurement that is at least as large as the average for that carat weight. There is no need to pay for the carat weight you can't see.


Q. What is Clarity?

A. Created by nature, most diamonds contain unique birthmarks called “inclusions” (internal) and “blemishes” (external). Diamonds with few birthmarks are rare and rarity affects value. Using the internationally recognized GIA Diamond Grading System, diamonds are given a clarity grade that ranges from flawless (F), to diamonds with more prominent inclusions (I3).


Q. What is Color?

A. Colorless diamonds are extremely rare and highly valued. Most diamonds are nearly colorless with yellow or brown tints. The GIA Diamond Grading System uses letters to represent colors, beginning with D (colorless) and ending at Z (light yellow or brown). The GIA Gem Trade Laboratory uses a Z masterstone to distinguish between normal range and "fancy" yellows. If a stone shows a natural yellow color slightly deeper than the Z master, its color is designated as "fancy light yellow" on the Diamond Quality Analysis Report.


Q. What is Cut?

A. The mere fact that there are traditionally 58 tiny facets in a diamond, each carefully cut and sharply defined, and may be only two millimeters in diameter, strikes many in the buying public as little short of miraculous. But this precision is essential to the potential beauty of a diamond. As a matter of fact, overall appearance – the brilliance, fire, and scintillation that makes diamonds uniquely beautiful depends more on cut than anything else. There are no internationally recognized grades for cut, as there are for color and clarity, and there are differences of opinion within the trade about some aspects of cut. Even the Federal Trade Commission is vague about it, compared to the rigor with which other aspects of diamond quality are described. But the affect of cut on a diamond's appearance is indisputable. The Gemological Institute of America (GIA) describes cut as the proportions and finish of a diamond or colored stone. Proportions are the size and angle relationships between the facets and different parts of the stone. Finish includes polish and details of facet shape and placement. Cut can also mean shape, as in round brilliant, emerald cut, or marquise cut.