How to Buy a Diamond

The value of a diamond is based on its size (weight) and its grading. Grading should only be accepted from a recognized independent grading laboratory. The GIA is the creator of the 4C’s (carat, cut, color, clarity) diamond grading system and is recognized both nationally and internationally as the world’s foremost authority in the grading of diamonds. This is why diamonds with a GIA certificate offer the best value.

All of our certified diamonds feature only the best grades for cut, depth and table percentages, polish, symmetry and fluorescence.

What Makes the Value of a Diamond?

The carat weight (size) of a diamond is the first determining factor in the price of a diamond. Once the shape and the size of a diamond are determined, the following key factors make up the overall cost and determine the diamond's value.


Carat weight is made up of points… like ounces to a pound. It takes 100 points to equal one carat. For example, 25 points = 1/4 carat, 50 points = 1/2 carat, etc. Various diamond sizes are shown below. However, please do not use these pictures as an absolute indicator of size. Due to the various sizes of computer screens, the diamond may appear on-screen larger or smaller than the actual stone.

Carat Weight:

0.5 Carat Diamond
0.50 Carat (5mm)
1 Carat Diamond
1.00 Carat (6.5mm)
1.5 Carat Diamond
1.50 Carat (7.5mm)
2 Carat Diamond
2.00 Carat (8mm)


When we buy diamonds we look first at the cut. The cut refers to how well the diamond is proportioned, not the shape. If cut properly it will have more brilliance and, as a result, will be more valuable than a poorly cut stone.The certificate will tell you how the stone is cut. Look at the depth and table percentages. Ideal percentages, for a round diamond, should be a table between 53% and 64% and a depth between 58% and 64%. In a princess cut, both table and depth percentages should be between 65% and 80%. If lower or higher than this range, the stone will be too shallow or too deep. Both will adversely affect the beauty and the value.

These are not cuts, they are shapes.
Shapes of Diamonds
These are cuts:
Cuts, not shapes
Diamond Table and Depth Percentages Table and Depth Percentages
Diamond Ratio of Length to Width Ratio of Length to Width


Clarity refers to a diamond’s internal quality. Grading is performed under 10 power magnification. The size and location of an inclusion determines the clarity grading.

  • FL= flawless
  • IF = internally flawless
  • VVS1/VVS2 = very, very slightly included
  • VS1/VS2 = very slightly included
  • SI1/SI2 = slightly included
  • I1/I2/I3 = included

Diamond Clarity:

FL (Flawless)
IF (Internally Flawless - minor surface blemishes
VVS1-VVS2 (Very, Very Small Inclusions)
VS1-VS2 (Very Small Inclusions)
SI1-SI2 (Small Inclusions)
I1-I2-I3 (Imperfect eye-visible inclusions)


Color grading according to The Gemological Institute of America (GIA) is as follows:

  • Diamond Color D E F D, E, F     = Colorless
  • Diamond Color G H I J G, H, I, J  = Near colorless
  • Diamond Color K L M K, L, M    = Faint yellow
  • Diamond Color N-Z N-R         = Very light yellow
  • Diamond Color N-Z S-Z          = Light yellow

Color Table:


About Enhanced Diamonds

Be sure you are not buying a diamond that has been altered or enhanced... The GIA has determined that some treatments are not permanent and therefore, these diamonds have a reduced value.

Key Factors that Make Up the Value of a Diamond

All J. Edwards graders are GIA graduates and thoroughly trained in buying diamonds. All J. Edwards certified diamonds must meet the specific grading parameters mentioned below. J. EDWARDS DIAMONDS is very strict in our grading.

  • Symmetry is the balance of the diamond… example, is the diamond round or is it off round?
  • Polish refers to the smoothness of the finish… example, does it have streaks or lines? GOOD, VERY GOOD, EXCELLENT is what we look for. Do not accept POOR OR FAIR.
  • Fluorescence refers to the material of the diamond.. NONE OR FAINT is acceptable... MEDIUM, STRONG, BLUE, HEAVY are not acceptable, as the diamond will appear hazy.
  • Light Performance ... Maximum brilliance and light performance is achieved as a result of proper cut, depth and table percentages, polish, symmetry and fluorescence. If any of these important factors are low grades, it will create light leakage and the diamond will lose its brilliance.

How to read the certificate

All of the information needed to determine the characteristics and value of a diamond are on a full laboratory certificate. A “mini” certificate, listing only size, color and clarity, should not be relied upon for determining value. Make sure that all characteristics are in terms related to the GIA. If other terms are used, it is impossible to determine the diamond’s true value.


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