Introduction to Diamonds
Diamonds burn brightly as symbols of love. For centuries, they have conquered hearts, launched romances, marked anniversaries. Kings and queens covet them. Movie stars flash them. Some of the planet's hottest and coldest spots produce them. In story and song, the desire for diamonds is as enduring as diamonds themselves. Sifting mountains of rock, in the harshest of climates, produces rough diamonds. A ton of diamond-bearing rock may yield half a carat. If it is earth's ability to squeeze carbon into the hardest substance known, it is the hand of man that coaxes out its luminous personality.

Slip a diamond on your finger and you wear a piece of geological history. Though diamonds are cut to rigorous standards, nature endows each with its own identity. Tiny quirks, most invisible to the naked eye, exist in the form of specks, bubbles and feather-like lines. Among the millions of carats mined each year, truly flawless diamonds number in the hundreds. These rarest of beauties are the costliest.

How diamonds are cut affects their brilliance. Traditional cuts radiate an almost incandescent spark of light. A modern version called the Ideal cut is said to trigger a rainbow of fire-like color. Debate over "light" and "fire" rages on. Which to buy is in the eye of the beholder. Both can be dazzling.

Certification: Your Guarantee of Value
The certificate is like your passport: it identifies and attests to the specific characteristics of your diamond. Apart from a diagram of your diamond's special quirks or inclusions, the certificate details its measurements and grades such characteristics as color, clarity and cut. The certificate assures that your diamond is what it claims to be.

You may also receive documents from other recognized certifying bodies. Look for names like the American Gem Society, Belgium High Council, International Gemological Institute and European Gemological Laboratory.

Choosing a Shape: Many Stunning Possibilities
Diamonds have tops and bottoms. The shape of a diamond is determined by the configuration of its girdle. The girdle refers to the largest perimeter that outlines the diamond and separates the top from the bottom. Picture what the girdle looks like from above. That tells you the diamond's shape-- round, oval, pear or some other. Shape will influence how a diamond is cut for maximum brilliance.

Here is what the main shapes look like:

While there are other shapes, these are the most popular. Round brilliant diamonds are by far the favorites, accounting for four of every five diamonds purchased.

Cut: The Source of The Sparkle
How a diamond is cut--so that all of its facets work in harmony to spark the greatest brilliance--is an art as much as it is a science. Among the 4C's of diamond value, including clarity, color and carat weight, cut is considered the most critical. Cut is what unleashes a diamond's singular beauty.

A number of special terms are used to describe the quality of a cut. It is enough to know that very good diamonds reflect up to 90% of the light entering from above. Good diamonds are equally well proportioned, but their reflective powers are less than their more highly graded relations. At the low end of reflectivity, fair and poor diamonds may reflect no more than 40% of the entering light.

Proportion plays a key role. A shallow cut diamond, where the bottom half lacks a certain depth, reflects light downward from its base. A diamond cut too deeply will emit light from the side of its base. Ideally cut diamonds, and therefore more perfectly proportioned stones, reflect most of their light through their table or top surface. This quality is the most prized and costly.

Color: Why a "D" Rating is Desired
Rarely does the absence of something add value. Not so for diamonds, where the absence of color is nearly always the mark of value. Diamonds purest in brilliance have no colors--reds, blues and violets--to conflict with their sparkle. The exception: Fancy colored diamonds that are extremely rare and prized for their deep hues. "Fancies" have brought at auction nearly a million dollars a carat.

Diamonds are graded on the basis of color. The Gemological Institute of America uses the letters "D" through "Z" to rank diamond color. Blue white diamonds, considered absolutely colorless, carry a top rating of "D". At bottom, diamonds with a yellowish caste carry a "Z" rating. To the untrained eye, variations among the leading grades are almost impossible to detect. "D"-rated diamonds cost more than those lower on the scale.

Judging color in the day-to-day world is often subjective. In the world of diamonds, determining color is an extremely objective and precise process. You would not mix "D"-rated diamonds in the same necklace with "H"-rated gems, even though they looked similar. Nor would you want to pay "F"-level prices for "J"-ranked stones. That's why a certificate from the Gemological Institute is so important when buying a diamond.

Clarity: Defining the Inner Beauty
Among the four "Cs" of diamond value, "clarity" embraces the inner appearance of diamonds. In keeping with the precise nature of determining diamond value, clarity has its own scale of measurement.

Nearly all diamonds have inclusions. Bubbles, specks and lines are inclusions that give each diamond its own inner signature. The clarity scale accounts for these microscopic imperfections. Gems with the fewest inclusions are the rarest and costliest. So minute are many inclusions that they can be seen only under 10-power magnification. That means your diamond may contain inclusions undetectable to the naked eye. A certificate from the Gemological Institute of America shows their location.

Carats: Unrivaled for the Weight
Whether the word carat comes from an African word meaning seed or from a Greek word meaning bean kernel is unknown. What is clear is that diamonds are measured in carats. One fifth of a gram equals one carat. If 454 grams equal a pound, or a thousand carats, then your weight in diamonds is worth a king's ransom indeed.

Larger diamonds, always rarer than smaller ones, are not simply priced proportionately more. Owing to its rarity, a two-carat diamond will cost more than two one-carat stones of equal quality. Small diamonds are weighed in "points" equal to 1/100 of a carat and priced accordingly.

A diamond's width increases with the number of carats. Though a five carat diamond is only less than twice the width of a one carat stone, its rarity and weight will command a price out of all proportion to the weight and price of the one carat gem.