History of the 4C’s

by GIA

How to Choose a Diamond

by GIA


Beyond the Four C’s of Diamonds

The process of selecting a diamond may seem overwhelming. But knowing the four Cs – Carat, Color, Clarity, Cut – will help you understand the characteristics of a diamond and make a perfect diamond purchase.  You can go beyond the Four C’s using specific cut angles and ratios; fluorescence can also play a role in your decision.  Fluorescence is a common misnomer in the market.  Yes, it can have a negative effect on a gemstone; but it can also have positive effects depending on the nature of the Four C’s.



One carat can equal to 0.2 grams or 200 milligrams. Carat Weight (ct) is the prime factor that determines the weight (not size) of a diamond. Larger diamonds can be undoubtedly costlier. The carat makes expressing diamond weight easier as compared to milligrams. Instead of giving three labels to diamonds weighing 20 milligrams, 211 milligrams and 220 milligrams, it is easier to express diamond weight using its own unit of Carat.

One should not forget that a higher carat weight does not necessarily mean a larger looking diamond. Even diamonds of the same weight can differ on a basis of other factors, considering it is a diamond’s cut that influences it’s perceived size. Large diamonds are rare to find and much more in demand as compared to smaller diamonds even of the same quality. The price of a one-carat solitaire diamond ring is usually more than a ring with smaller diamonds consisting of the same total carat weight. Diamond comparison is not effective until you compare the diamonds of similar features and qualities. It can help viewing them in person.  You can also compare the value of different diamonds; divide the total cost of the diamond by it’s carat weight to calculate its price per carat.  A diamond that is set cannot be weighed.  However, if you can obtain measurements using a millimeter gauge, there are several formulas one can use to calculate the carat weight of the diamond.  Keep in mind, these formulas are not as precise as a carat scale, but they will prove to be useful if the diamond is mounted.


Estimating Carat Weight



When a jeweler refers to a diamond’s color, he is actually pointing to the absence of the color or trace elements in the diamond. Color of a diamond is a result of a diamond’s composition and does not change with time. Colorless diamonds allow light to travel through them differently as compared to diamonds with color. These diamonds also can emit more fire and sparkle. The process, through which a diamond is formed, decides its color factor. The more colorless the diamond, is the higher value it will have when pertaining to the GIA “D-Z” Color Grading Scale.  This scale does not apply to Fancy Colored Diamonds.  See a gemologist for more information on Fancy Colored Diamonds.

Upon grading the Color of a diamond, most jewelers refer to GIA’s Color Scale that starts at the completely colorless rating (“D”) and scales down to a light yellow or brown (“Z”) as traces of color and saturation are found. Diamonds graded from D to J are among the most desirable and demanded stones. These diamonds are colorless and near colorless. Nevertheless, if you have a lower budget, you can also find beautiful diamonds with lower color grades. These diamonds are not exactly colorless but show no color to untrained eye when they are set face up in an engagement ring.

Consider the setting of the diamond before choosing the color grade of a diamond. If the setting for your diamond is platinum or white gold, opt for a higher color grade (D-J), if you want to get it fitted in yellow gold, slightly lower color graded diamonds can also look great. While you will find faint yellow starting at “K,” diamonds that are graded along the “K to Z” scale can be camouflaged or embellished by choosing the right setting for the stone. Many people prefer the warm glow given off by lower color grades and will generally save themselves money.



Approximately one-third of the diamonds in the market give off fluorescence.  When diamonds are exposed to long-wave ultraviolet light they can fluoresce.  This does include sunlight and other sources.  Under most lighting conditions, this effect cannot be seen by the naked-eye.  Some people prefer diamonds without fluorescence where as some others may look for this characteristic.  It is all about the aesthetics and the nature of the diamond.  A professional can certainly give you more advise.



Diamond clarity means finding out the characteristics of a diamond, or it’s inclusions.  INCLUSIONS are naturally occurring internal formations that are found in diamonds, such as crystals, feathers, and clouds.  Clarity grades are assigned to diamonds under a loupe with 10X magnification. The grades given to a diamond fall along the GIA Clarity Grade Scale.  The scale begins with a “Flawless” grade and ends with “I3” (Included 3- obvious inclusions that can affect the integrity of the diamond.)  Just as fingerprints are unique to an individual, inclusions are unique to a diamond.  For this reason, diamonds are mapped to prove their identity.

BLEMISHES are the external characteristics of a diamond.  Most blemishes can occur at the time of cutting or manufacturing a diamond. Blemishes include features like abrasions, nicks, rough girdles or even extra facets.

Diamonds that have the least amount of blemishes and inclusions are considered the most valuable.  Diamonds that fall within “VVS and VS” grades usually command a premium.  They are perfect in regard to the terms of appearance and value. However, “SI” (Slightly Included) grades are even less expensive options and generally cannot be see by the naked eye.  This makes the SI grade “fit the bill” for a lower budget.  You can also invest in less expensive options like I1 diamonds.  If you mount the diamond just right within it’s setting, you can mask the set grade using a prong.


Plotting a Diamond

Lab Reports by leading laboratories, such as GIA and AGS, may consist of a Diamond Plot.  Again, because there is no similarity between two diamonds, a plot or mapping confirms the identity of the diamond.  It can give you assurance that the diamond you are receiving is the diamond you paid for.  In addition, a diamond plot will help guard against theft and give you certain clarity knowledge of your diamond by locating each characteristic.  Diamond Characteristics are plotted using Red and Green colors.  Red ink signifies Inclusions; Green ink signifies Blemishes.

The Stages of Diamond Clarity



Cut should always be your first priority.  A Diamond’s Cut is it’s make; the process of manufacturing a finished gemstone from rough, raw elements.  People often confuse diamond shape with diamond cut. The shape of the diamond is the outward appearance it has. When referring to Cut, we refer to the brilliance and reflective qualities of the diamond; not it’s shape. A diamond’s quality is a crucial part of the 4C’s. A great cut gives a diamond life.  It provides brilliance, fire, and scintillation to the diamond.  It is only after the cutting process that a diamond can dance with light.

The formula is in the proportions of the diamond, especially in the context of how Depth and Table Percentages occur with each other.  If you are buying a diamond without a Certified Lab Report, at least be sure your diamond has been reviewed by a gemologist.

Variances in cut percentages and angles are difficult to detect by the casual observer. As cut is extremely important, you can make use of different grading methods for determining the cut of a specific diamond. When it comes to Fancy Shaped Diamonds, the selection of Cut grade is usually based on a person’s preference of shape appeal.  For making the best selection, one needs to be acquainted with different types of shapes and their cut ratios.  “Cut” grades are noted below:

“Very Good” diamond cuts reflect an extremely great amount of light return.  They provide a combination of brilliance, sparkle, and fire considered exquisite enough to the diamond while saving you cost.

“Good” diamond cuts can reflect most of the light that passes through them. The proportion of these diamonds is outside the preferred range. Diamonds that fall under this category will sometimes allow you to save money without compromising on the beauty and quality of the diamond.

“Fair and Poor” quality diamond cuts reflect a small portion of light that enters into them. The light generally falls straight through the diamond if it is cut too shallow; it bounces off the pavilion facets and falls out the side should the diamond be cut too deep.  These diamonds are usually cut in order to save carat weight above all other considerations.  They are usually much lower in cost.


The “Ideal Diamond Cut,” by matter of professional opinion, provides maximum brilliance to a diamond. The Table and Depth Percentages (60/60) of these diamonds also work in the best possible way to create the most fire and sparkle. With Ideal Cut diamonds, you can be sure to get some of the finest quality of light shows in town.  This category is just for Round Brilliant Cut diamonds. Premium Cuts, known as “Triple-X” Cuts, are also equivalent to Ideal Cuts in round diamonds.  This is where the Cut and Finish (Symmetry & Polish) of a GIA graded diamond are all “Excellent.”


Finish is the last step to the Cut.  The Finish of a diamond is accredited to the combination of two things; it’s Symmetry and Polish.  This is also indicative of an extraordinary cut.  Generally, not falling short of a GIA grade of “good” for both symmetry and polish is recommended.  Yet, there are instances where finishes in a Fancy Cut diamond have been determined as “fair” and still look amazing.

Making the Cut

The Faces or Facets

of a Diamond