THE 4 C'S DIAMOND GRADING SYSTEM:
CUT • CLARITY • CARAT WEIGHT • COLOR
In the United States every year there are about 100 million diamonds that are sold to everyday consumers. Most of these consumers know very little about the products that they are purchasing. There is a lot more to it than just a diamond band or a diamond pendant.
A diamond is a beautiful piece that derives from our planet. The value of this unique stone can be represented by the 4 C’s. This classification is used worldwide and represents the four main variables that are used to calculate the quality and value of a diamond.
These diamonds are assessed by various diamond graders both as a rough and a cut diamond.
When shopping it is your first step while shopping for a diamond to learn about the 4C’s and how it relates to the item that you are purchasing. You will also want to familiarize yourself with the Federal Trade Commission (FTC) guidelines on jeweler conduct and consumer awareness. This knowledge will help be invaluable when you are comparison shopping for diamonds.
The cut of the diamond is one of the most important factors to consider. The cut of the diamond is about 60% of the value. The cut is known to vary based on the shape of the stone, location of the inclusions and its flaws. It is important that while eliminating the flaws of the diamond cutting its cutting process to preserve the weight and along the light reflection to enhance the beauty of a diamond’s shape. Previous years ago the Cut part of the diamond was undervalued and difficult for a customer to understand because before only a trained professional could see the quality of a good cut. Now AGS rating system and GIA's new "Cut Grading System" has allowed individuals to become more educated.
If a diamond has a high quality cut grade like an ideal cut, it allows more light reflection to enter the stone through the table and the crown. The way that it does this is by traveling toward the pavilion where it reflects from one side to the other before it bounces back out of the diamond’s table as it goes into the observer’s eye. This is also known to be the light return. The light return affects a diamond’s brightness, brilliance and dispersion. Any light-leakage that occurs either from poor symmetry and or the cut proportions will affect the light return .
The "Shallow Cut" and "Deep Cut" examples in Figure listed below show how light that enters through the table of a Modern Round Brilliant diamond reaches the pavilion facets and then leaks out from the sides or bottom of the diamond rather than reflecting back to the eye through the table. Less light reflected back to the eye means less "Brilliance". In the "Ideal Cut" example, most of the light entering through the table is reflected back towards the observer from the pavilion facets.
There are various cut qualities that are divided into several grades listed.
Very Good / Fine Cut
An Ideal Cut or Premium Cut "Round Brilliant" diamond has the following basic proportions according to the AGS:
Table Size: 53% to 60% of the diameter
Depth: 58% to 63% of diameter
Crown Angle: 34 to 35 degrees
Girdle Thickness: medium to slightly thick
Facets: 58 (57 if the culet is excluded)
Polish & Symmetry: very good to excellent
The girdle on a Modern Round Brilliant can have 32, 64, 80, or 96 facets which are not counted in the total number of facets (58). The crown will have 33 facets, and the pavilion will have 25 facets. Other variations of the "Modern Round Brilliant" include the "Ideal Brilliant" which was invented by Johnson and Roesch in 1929, the "Parker Brilliant" invented in 1951, and the "Eulitz Brilliant" invented in 1972.
Poor Diamond Faceting and Symmetry
For a Modern Round Brilliant cut (Tolkowsky Brilliant), there is a balance between "brilliance" and "fire". A diamond cut for too much fire will look like cubic zirconia, which gives out much more fire than a real diamond. A well executed round brilliant cut should reflect the maximum amount light from the interior pavilion facets, out through the table, making the diamond appear white when viewed from the top. A cut with inferior proportions will produce a stone that appears dark at the center (due to light leaking out of the pavilion) and in some extreme cases the ring settings may show through the top of the diamond as shadows.
BALANCING CUT AND WEIGHT
A carat can also be divided into "points" with one carat being equal to 100 points, and with each point being 2 milligrams in weight. Therefore, a 1/2 carat diamond would be 50 points, a 3/4 carat diamond is 75 points, and a 2 carat diamond is 200 points.
When a single piece of jewelry has multiple stones, the total mass of all diamonds or gemstones is referred to as "Total Carat Weight" or "T.C.W. The word "Carat" is derived from the Greek word keration, or "seed of the carob". In ancient times, carob seeds were used to counterbalance scales, and as a benchmark weight due to their predictably uniform weight.
NOTE: YOUR SCREEN RESOLUTION MAY ALTER THE REPRODUCTION SIZE OF THE CHART ABOVE. THIS CARAT/MILLIMETER SIZING CHART IS MEANT FOR COMPARISON PURPOSES ONLY.
Clarity is one of the Four C's, representing the four variables that are used to calculate the quality and value of a diamond. The term "Clarity" refers to the presence or absence of tiny imperfections (inclusions) within the stone, and/or on the surface of the stone.
All of the grades of diamond clarity shown in the table below, at 10x magnification Higher magnifications and viewing from other angles are also used during the grading process.
DIAMOND CLARITY DESIGNATIONS
FL - "Flawless" no inclusions at 10 x magnification
IF - "Internally Flawless" no inclusions at 10 x mag. - small blemishes
VVS-1 - "Very Very Small" inclusions hard to see at 10 x magnification
VVS-2 - "Very Very Small" inclusions. VVS1 better than VVS2
VS-1 - "Very Small" inclusions visible at 10 x mag. - not naked eye
VS-2 - "Very Small" inclusions VS1 is better grade than VS2
SI-1 - "Small" or "Slight" Inclusions or "Imperfections" may be "eye clean"
SI-2 - "Small" or "Slight" Inclusions or "Imperfections" visible to naked eye
SI-3 - Inclusions large and obvious, little or no brilliance
I1 to I3 - Imperfect, with large Inclusions, fractures, and flaws
INTERNAL DIAMOND INCLUSIONS
Carbon - Tiny black spots caused by carbon inclusions.
Clouds - Cloudy grouping of tiny pinpoints that may not resolve at 10X Magnification.
Feathers - Cleavage planes or internal fractures that have the appearance of feathers.
Grain Center - Concentrated area of crystal growth that appear light or dark.
Internal Graining - Irregular crystal growth causing internal distortions, waviness, haze.
Needles - Rutile-like needle inclusions.
Pinpoints - Minute crystals within the diamond that appear white.
Pique - Garnet or other Included gem stones
Twinning Wisps - Inclusions resulting from crystal twinning during growth.
EXTERNAL DIAMOND INCLUSIONS
Bearded Girdles - Fine cracks, chips, fringing, or feathers along the outer edge of girdle.
Bruising - A percussion mark caused by impact.
Cavities - An indentation resulting from a feather or damage during polishing.
Chips - Damage usually occurring on the sharp edge of a facet.
Knots - An inclusion that penetrates the surface, appearing as a raised area.
Indented Naturals - A natural indentation that was not removed by polishing.
Filled Fractures - Fractures that have been artificially filled.
Pits - Dislodged pinpoint inclusions at the surface.
Surface Graining - Visible surface lines caused by irregular crystallization during formation.
Most all natural diamonds contain small quantities of nitrogen atoms that displacing the carbon atoms within the crystal's lattice structure. These nitrogen impurities are evenly dispersed throughout the stone, absorbing some of the blue spectrum, thereby making the diamond appear yellow. The higher the amount of nitrogen atoms, the yellower the stone will appear.
D, E, F - colorless (white)
G, H, I, J - near colorless
K, L, M - faint yellow or brown
N, O, P, Q, R - very light yellow or brown
S, T, U, V, W, X, Y, Z - light yellow or brown