DIAMOND QUALITY FACTORS
One of the first things most people learn about diamonds is that not all diamonds are created equal. In fact, every diamond is unique. Diamonds come in many sizes, shapes, colors, and with various internal characteristics.
All polished diamonds are valuable. That value is based on a combination of factors. Rarity is one of those factors. Diamonds with certain qualities are more rare—and more valuable—than diamonds that lack them.
Jewelry professionals use a systematic way to evaluate and discuss these factors. Otherwise, there would be no way to compare one diamond to another. And there would be no way to evaluate and discuss the qualities of an individual diamond. Diamond professionals use the grading system which established the use of four important factors to describe and classify diamonds: Clarity, Color, Cut, and Carat Weight.
These are known as the 4Cs. When used together, they describe the quality of a finished diamond. The value of a finished diamond is based on this combination.
A diamond’s value is often affected by the rarity of one or more of the 4Cs. Colorless diamonds are scarce—most diamonds have tints of yellow or brown. So a colorless diamond rates higher on the color grading scale than a diamond that is light yellow. Value and rarity are related: In this case a colorless diamond is more rare and more valuable than one with a slight yellow color. The same relationship between rarity and value exists for clarity, cut, and carat weight.
The 4Cs describe the individual qualities of a diamond, and the value of an individual diamond is based on these qualities. The terms that people use to discuss the 4Cs have become part of an international language that jewelry professionals can use to describe and evaluate individual diamonds.
Today, the descriptions of each of the 4Cs are more precise than those applied to almost any other consumer product. And they have a long history. Three of them—color, clarity, and carat weight—were the basis for the first diamond grading system established in India over 2,000 years ago.
Subtle differences in color can dramatically affect diamond value. Two diamonds of the same clarity, weight, and cut can differ in value based on color alone. Even the slightest hint of color can make a dramatic difference in value.
Diamonds come in many colors. Diamonds that range from colorless to light yellow and brown fall within the normal color range. Within that range, colorless diamonds are the most rare, so they’re the most valuable. They set the standard for grading and pricing other diamonds in the normal color range.
Many diamonds emit a visible light called fluorescence when they’re exposed to ultraviolet (UV) radiation. Although invisible to the human eye, UV radiation is everywhere. Sunlight contains it. Fluorescent lights emit it, too. Under the right conditions, you can see fluorescence in about 35 percent of gem diamonds.
Blue is the most common fluorescent color in gem-quality diamonds. In rare instances, fluorescence can be white, yellow, orange, or many other colors.
Strong blue fluorescence can make a light yellow diamond look closer to colorless in sunlight. Blue and yellow are color opposites and tend to cancel each other out, so blue fluorescence masks the yellow color. If the fluorescence is too strong it can make the stone look cloudy or “oily,” which can lower the value of the diamond.
Few things in nature are absolutely perfect. This is as true of diamonds as anything else. Diamonds have internal features, called inclusions, and surface irregularities, called blemishes. Together, they’re called clarity characteristics. Clarity is the relative absence of inclusions and blemishes.
Among other things, blemishes include scratches and nicks on a diamond’s surface. Inclusions are generally on the inside, and some might break the surface of the stone. Sometimes, tiny diamond or other mineral crystals are trapped inside a diamond when it forms. Depending on where they’re located, they might remain after the stone has been cut and polished, and they can affect a diamond’s appearance.
Clarity characteristics might have a negative influence on a diamond’s value, but they can have positive effects as well. For one thing, they help gemologists separate diamond from imitations. (This is easier with included diamonds than with flawless ones.) And because no two diamonds have exactly the same inclusions, they can help identify individual stones. They can also provide scientists with valuable information about how diamonds form.
ike the rest of the 4Cs, clarity’s influence on value is directly related to the concept of rarity. Flawless is the top grade in the Clarity Grading System. Diamonds graded Flawless don’t have visible inclusions or blemishes when examined under 10-power (10X) magnification by a skilled and experienced grader.
A beautifully finished diamond is dazzling, with every facet displaying the craftsman’s skill and care. When a diamond interacts with light, every angle and every facet affects the amount of light returned to the eye. This is what gives it its face-up appearance.
A diamond’s proportions determine how light performs when it enters the diamond. If light enters through the crown and goes out through the pavilion, the diamond will look dark and unattractive. Diamonds with different proportions and good polish make better use of the light, and will be bright, colorful, and scintillating.
A well-cut diamond displays the beauty consumers expect to see in a diamond.
A beautiful diamond looks the way it does because of three optical effects: white light reflections called brightness, flashes of color called fire, and areas of light and dark called scintillation. Pattern is the relative size, arrangement, and contrast of bright and dark areas that result from a diamond’s internal and external reflections. There must be enough contrast between the bright and dark areas to give the pattern a crisp, sharp look.
Many goods are sold by weight—by the kilogram, ounce, pound, or ton. Even people who have never bought a diamond are used to the idea that weight and price are related. They understand that a larger diamond is probably more valuable than a smaller one. But there are two things that often surprise people when they start learning about diamonds and carat weight.
The first is the precision with which diamonds are weighed. Diamond weights are stated in metric carats, abbreviated “ct.” One metric carat is two-tenths (0.2) of a gram—just over seven thousandths (0.007) of an ounce. One ounce contains almost 142 carats. A small paper clip weighs about a carat.
The metric carat is divided into 100 points. A point is one hundredth of a carat.
Diamonds are weighed to a thousandth (0.001) of a carat and then rounded to the nearest hundredth, or point. Fractions of a carat can mean price differences of hundreds—even thousands—of dollars, depending on diamond quality.
Over a carat, diamond weights are usually expressed in carats and decimals. A 1.03-carat stone, for example, would be described as “one point oh three carats,” or “one oh three.” Weights for diamonds that weigh under a carat are usually stated in points. A diamond that weighs 0.83 carat is said to weigh “eighty-three points,” or called an “eighty-three pointer.”
The relationship between rarity, weight, and value can be surprising. People know that a pound of sugar costs twice as much as a half-pound of sugar. But diamonds aren’t a commodity like sugar. Their price depends on a number of variables—weight is just one of them. So it’s not always easy to understand, or explain, why a 1-carat diamond is worth, say, $6,000, while a 2-carat diamond of similar quality might be worth $15,000.
It’s really a simple concept: Large diamonds are more rare than small diamonds. The more scarce something is, the more it is worth. So a larger stone doesn’t just cost more. It also costs more per carat. A 1-carat diamond weighs the same as four 0.25-carat diamonds. But even if all the other quality factors are equal, the larger diamond is worth much more than the sum of the four smaller diamonds.
Carat weight can also be symbolic. While the visual difference between a 0.98-carat diamond and a 1.01-carat diamond is negligible, many people will opt for the larger stone—even at a much higher price. Some weights are considered “magic sizes”: half carat, three-quarter carat, one carat, etc. There’s not much difference in their weights, but if both are D-color round brilliants with identical clarity and cut, the size makes all the difference. They really don’t look much different, but if a consumer’s heart is set on the one-carat size, the difference is enormous. The fact that the second stone is slightly over the “magic” one-carat size can give it as much as a 20 percent difference in price with only a 6-point difference in weight.
Don’t confuse the term carat with karat. Karat is a unit of measure used to describe how much pure gold there is in an alloy.