Grading

Carat Weight

Carat Weight is the most commonly known tool in distinguishing the value of a diamond. Many times it is the first or only descriptor given to convey the value of a particular stone. Simply put, when measuring the weight of a diamond rather than using grams or ounces jewelers use a smaller measurement called carats. Carats are measured with points and each carat is 100 points. When a diamond weighs 50 points it equals a half a carat. Sometimes you may hear diamond weight referred to in “grains” which are equal to 25 points or a quarter carat and a single carat diamond may be referred to as a “four grainer.” To provide uniformity worldwide the standard for one gram of diamonds is 5 carats.

Due to the way natural diamonds are formed, as the size of the diamond increases so does the rarity. While a quarter carat diamond is rather common, something as small as a single carat is much harder to find and multiple carat stones are highly valued and sought after.

Be careful not to confuse weight with size. While stone size usually increases with weight, the carat is a weight measurement and can be affected by the density of the stone. This becomes important when precise measurements are needed when mounting the stone in a particular setting.

Clarity

Clarity of a diamond is determined by the type, size, number, position, and contrast of what are known as “inclusions”. Inclusions are imperfections in the stone such as carbon that was not fully crystallized or other minerals that were trapped within the diamond as it was created. Contrast is of particular importance because dark inclusions are more noticeable imperfections than grey or white and have more of an effect on the dazzle of a diamond. Position is important since the wrong position of a single inclusion can cause it to be reflected many times when viewing the stone. Diamonds may also contain blemishes which are on the outer surface rather than inside the stone.

The most commonly used scale used to express clarity is from the Gemological Institute of America (GIA). This scale is broken down into 6 basic categories with subcategories in each as seen here:

Flawless (no inclusions under a 10x loop magnifier)
IF (internally flawless, surface blemishes exist)
VVS 1, 2 (very very slightly included: minute inclusions)
VS 1, 2 (very slightly included: minor inclusions)
SI 1, 2 (slightly included: noticeable inclusions)
I 1, 2, 3 (included: observable inclusions)

Diamond grading is performed with a 10x magnifier called a loop, but I1, I2, and I3 inclusions can be seen with the naked eye. Sometimes the word imperfection is used rather than inclusion however the grading remains the same.

A note of caution, while clarity effects brilliance it does not always denote brilliance. Without a jeweler’s loop, the difference between flawless and slightly included can be indistinguishable and an imperfect stone can be cut to enhance the brilliance despite the inclusions.

Suggested Reading:  AGS vs. GIA Grading.

Color

Although diamonds are regarded by most people as a colorless clear stone. Color is an important consideration for determining the quality of a diamond. Diamonds are not only clear and colorless but can come in hues of most commonly yellow but can also appear brown or grey. The GIA offers the following color scale ranging from D to Z, with D being colorless and clear and Z being heavily colored.

Colorless (D, E, or F)
Near Colorless (G, H, I, or J)
Faint Tint (K, L, or M)
Very Light Tint (N, O, P, Q, or R)
Tinted Light (S, T, U, V, W, X, Y, or Z)

When viewing the grade of a diamond a non-reflective white background is important since something as small as clothing color, lighting, and instrument color can affect the grade.

Some diamonds have a unique, intense natural color and are referred to as “fancy”. The fancy appearance of these stones, which can be quite rare, can dramatically affect value.
Due to the uniqueness in color, the GIA scale is not used for fancy diamonds that come in red, blue, purple, or green.

Cuts

A properly cut diamond will enhance two main attributes of the stone, fire, and brilliance. Fire is the refractive rainbow of colors that appear inside the diamond and brilliance is the sparkle of light that reflects within the stone. Releasing the fire and brilliance requires precise faceting, symmetry, proportion, and finish (or “make”).

The three main styles of cutting stones are brilliant cut, step cut, and mixed cut. Brilliant cut enhances the sparkle or brilliance of the stone by using many triangle and kite-shaped facets. Step cut focuses on elegance with fewer cuts and more trapezoids and rectangles. Mixed combines the brilliant and step cut styles to enhance the unique beauty of the stone. If a diamond is improperly cut then light is lost through the bottom or sides reducing the brilliance and overall appeal of the stone.

A multitude of variations to the three basic cuts that provide a wide range of choices when considering which stone is most appealing. Some of the more popular cuts include baguette, emerald, marquise, pear, and spinfire but these are only a few of the available cuts. Many cut guides are available to help when considering which cut is preferable.

Ready to Shop

Now that you know the 4 C’s of diamonds you are ready to begin the hunt for the perfect stone. Remember, everyone has different tastes and ultimately the beauty of the stone is in the eye of the beholder but the 4 C’s of diamonds give you a good place to start.