Diamonds: The 4 Cs

We at Joshua's Jewelry Inc. have created this education page to help you better understand our excellent quality. We are available to answer any questions you have in regards to our diamond cut, clarity, and color.

Four factors are used to judge the quality of diamonds. These are the "4 C’s": cut, clarity, color and carat weight. Here, you will learn what each of the C's means and how it affects the value of the diamond. While it takes training to actually see these factors, if you know what they mean, you can make an informed choice in selecting your diamond.

Cut:

Diameter: The width of the diamond through the girdle.
Table: The largest facet at the top.
Crown: The top part from the girdle to the table.
Girdle: The narrow band around the widest part of a diamond.
Pavilion: The bottom part from the girdle to the culet.
Culet: The facet at the bottom tip. The preferred culet is not visible to the naked eye (graded "small" or "none").
Depth: The height from the culet to the table.

The cut of a diamond determines how well it reflects light. This reflection is responsible for the gem’s brilliance or sparkle. Skilled professionals cut the stone to mathematically exact proportions so as much light as possible reflects from each of its mirror-like facets out the top of the diamond. The diameter and depth of the gem affect how light travels within it and how light exits in the form of brilliance. If the cut is too shallow, light escapes out the sides and the diamond loses brilliance. If the cut is too deep, light is lost out the bottom and the diamond appears dark or dull.

This is why many gemologists consider a diamond’s cut to be the most important of its properties. Even if the stone has perfect color and clarity, a poor cut can make a diamond lack brilliance. A better cut gives a diamond its brilliance, beauty and value.

The cut of a diamond refers not only to the quality of the cut, but also to the shape of the diamond and the number of its facets. A diamond with poorly proportioned facets won't be given the same grade of cut as an ideally proportioned, masterfully cut stone.

Often people confuse a diamond's shape with its cut. This is due to the jewelry industry's synonymous use of the terms “cut” and “shape” to describe a diamond’s shape; for example, “Marquise-Cut” or “Pear-Shape.”

The traditional round shape provides a combination of the best qualities a diamond can have. There are other shapes that emphasize a diamond's different features. Your choice of a shape is best based on the design of the jewelry and your personal taste.

Despite its shape, the cut of a diamond refers to a combination of two factors: its proportions and the qualities of its finish.

The proportions of a well-cut diamond cause it to reflect light back to the eye evenly, with no dark areas. The diamond’s depth compared to its diameter, and the diameter of the table compared to the diameter of the diamond, determine how well light will reflect and refract within the stone. Diamond graders take into account the following proportions: length to width ratio, outline balance, profile balance, total depth percentage, crown height, pavilion depth, table size and bulge.

Finish refers to those qualities the diamond cutter gives to the stone. This includes every aspect of a diamond's appearance other than its intrinsic nature when it came out of the ground. Finish is divided into two categories: polish and symmetry.

Polish refers to the overall surface smoothness of the diamond's facets. The quality of the polish influences the ability of light to reflect from a diamond’s facets. With a poor polish, the surface of a facet may be dull, leading to a blurred or diminished brilliance. As they polish a diamond, sometimes cutters encounter variations in hardness or grain, resulting in microscopic polish lines running across a facet, small surface nicks or scratches. These characteristics lead to a lower rating for polish on a certificate, but rarely is the polish of a diamond so bad that it mars its beauty.

Symmetry refers to how well the points of each facet align with each other and the consistency of facet shape. In a diamond with poor symmetry, light may be misdirected as it enters and exits the gem. When a diamond is graded for symmetry, its actual shape and proportions are not considered. It may have poor proportions and still be rated Very Good in symmetry if its facets are equal and the overall shape of the diamond is balanced. Some of the more common symmetry faults diamond graders find are facets that are out of alignment, facet points that do not meet, round-brilliant diamonds that are "out-of-round" and diamonds with an off-center table.

When grading a diamond, an expert calculates its measurements and applies them to a cut grading scale that makes it easy to understand how well each grade reflects light. Diamonds carry cut grades of Excellent, Ideal, Very Good, Good, Fair or Poor:

• Excellent grade represents about the top 1% of diamond cut quality. The highest grades of polish and symmetry allow it to reflect the greatest amount of light.
• Ideal grade represents about the top 3% of diamond cut quality. It reflects almost all the light entering the diamond.
• Very Good grade represents about the top 15% of diamond cut quality. It reflects almost as much light as the Ideal grade, but for a lower price.
• Good grade represents about the top 25% of diamond cut quality. It reflects most light that enters it. Good grade is much less expensive than Very Good.
• Fair grade represents about the top 35% of diamond cut quality. A diamond with a Fair grade is still a quality diamond, but will not be as brilliant as a Good grade.
• Poor grade includes all diamonds that do not meet the proportion standards of a Fair grade. These diamonds are shallow and wide or deep and narrow; they lose most of their reflections out the sides and bottom.

Clarity

It is common for diamonds to have slight imperfections; an absolutely perfect diamond is a rarity. “Inclusions” are internal irregularities in the form of tiny white points, dark dots or feathery cracks. Viewed under a jeweler's 10x magnifying loupe or microscope, inclusions can look like crystals, tiny rivers or clouds. “Blemishes” are surface irregularities on a diamond.

Clarity is an important factor in determining a diamond's value. Experts grade a diamond's clarity on the number, size, type and location of inclusions and blemishes. A diamond with greater clarity will have greater brilliance and value. A gem with only a few hard-to-see blemishes where they can be covered by the mounting has better clarity than one with an inclusion right under the table.

The following are the clarity grades for diamonds when observed under 10X magnification by an experienced grader:

(FL) Flawless diamonds show no inclusions or blemishes of any sort internally or externally.

(IF) Internally Flawless diamonds have no internal inclusions and only very minor blemishes.

(VVS) Very, Very Slightly Included diamonds are graded within one of two subcategories: VVS1 and VVS2. In both, inclusions are extremely difficult to see. Typical inclusions are internal graining, faint clouds, tiny feathers or a few tiny pinpoints.

(VS) Very Slightly Included diamonds are graded within one of two subcategories: VS1 and VS2. These have minor inclusions impossible to detect with the naked eye. Typical inclusions are small-included feathers, clouds, crystals and groupings of pinpoints.

(SI) Slightly Included diamonds are graded within one of three subcategories: SI1, SI2 and SI3. Inclusions are easily detectable and centrally located. Under close examination, an inclusion may even be visible to the naked eye, but when mounted in jewelry it is not visible. Typical inclusions are included feathers, crystals and clouds.

(I) Imperfect diamonds are graded within one of three subcategories: I1, I2 and I3. Inclusions are very obvious under 10x magnification and may be visible to the naked eye. Typical features are large included crystals and feathers.

Color

Most people think of diamonds as white or colorless. In fact, diamonds come in a multitude of colors. Most diamonds may appear colorless, but actually have slight tones of yellow or brown. That color can lessen a diamond's brilliance. As a prism, a diamond divides light into a spectrum of colors and reflects it as colorful flashes called fire. Color in a diamond will act as a filter to diminish the spectrum of reflected light. The less color in a diamond, the more colorful the fire, and the better the color grade.

Color in diamond grading refers to subtle differences in hue. It is difficult for the untrained eye to notice such variations in color unless gems are compared side by side. The diamond color grading scale uses the letters of the alphabet, beginning at “D” (colorless) and going to “Z” (heavily tinted yellow). Only a highly skilled professional can detect any color in “E” or “F” grades. Near-colorless diamonds “G” to “J” often appear colorless when mounted in jewelry. The average consumer may begin to see a subtle presence of color around “J” grade. Most consumers can notice color in the range “K” to “M.” In grades lower than “M” it is very easy for consumers to see color. Not much jewelry is set with diamonds lower than “O” grade.

The color grade scale:
D: Absolutely colorless. This is the highest color grade; it is extremely rare.
E: Colorless. An expert gemologist can detect only minute traces of color. A rare diamond.
F: Colorless. An expert gemologist can see slight color, but this is still considered a “colorless” grade. A high-quality diamond.
G-H: Near-colorless. Color is noticeable when compared to diamonds of better grades, but these grades offer excellent value.
I-J: Near-colorless. Color is slightly detectable. A very good value.
K-Z: Increasing amounts of color are noticeable.

Although diamonds come in a wide variety of colors, colorless diamonds have traditionally been considered the most valuable. The closer the diamond comes to colorless, the more valuable it is. Actual colorless diamonds graded “D” to “F” are very expensive. If you are a purist, look for a colorless diamond with a grade of “D” to “F” and a fluorescence grade of none, faint, inert or negligible. If you want an excellent value, look for a diamond with a near-colorless grade of “G” to “I” and a fluorescence grade of medium or strong blue.

Any diamond you buy should have a good balance of cut, color and clarity. Even when a stone has a visible tint, such as grade “K” or above, it can still be very lovely if it has good clarity and cut.

Carat

Carat is the measuring unit of diamond weight. The definition of a carat has changed over time, but since 1913 the international standard has been 200 milligrams, or 1/5 of a gram. One carat is divided into 100 parts, called “points.” So, a 25-point diamond weighs a quarter carat and a 50-point diamond weighs a half carat. A diamond may be referred to as a 3/4-carat or 75-point stone.

Jewelers usually express diamond weights in carats and decimals. A 1.09-carat stone, for example, is said to weigh “one oh nine carats” while a 0.99-carat diamond weighs “ninety-nine points.”

“Carat total weight” (Ct. T.W.) describes the combined total weight of all the stones in a piece of jewelry having more than one diamond.

As diamonds are mined, larger stones are found much less frequently than smaller ones. This makes large diamonds much more valuable. The more rare the diamond, the greater its worth. In fact, diamond prices tend to rise exponentially with carat weight. A larger stone costs more per carat. So, all other factors being equal, a 0.50-ct. diamond will cost more than twice that of a 0.25-ct.; a single 2-carat diamond will cost much more than two 1-carat diamonds of the same quality. Also, you will pay a premium for stones that are above a full carat weight. For example, a .95-carat diamond will cost somewhat more than a .90-carat stone, but a 1-carat stone will cost significantly more than a .95-carat diamond.

Bigger is not always better. A diamond's ultimate value is based on a balance between the 4C's: cut, clarity, color and carat weight. None of these factors is automatically more important than the others. All of them must be considered together to determine the true worth of a diamond.