DIAMOND CUT
Diamond Cut Quality
When jewelers judge the quality of a diamond cut, or "make", they often rate "Cut" as the most important of the "4 Cs." The way a diamond is cut is primarily dependent upon the original shape of the rough stone, location of the inclusions and flaws to be eliminated, the preservation of the weight, and the popularity of certain shapes. Don't confuse a diamond's "cut" with it's "shape". Shape refers only to the outward appearance of the diamond and not how it is faceted.
The Importance of Cut Quality
When a diamond has a high quality cut (ideal cut), incident light will enter the stone through the table and crown, traveling toward the pavilion where it reflects from one side to the other before bouncing back out of the diamond's table toward the observer's eye. This phenomenon is referred to as "light return" which affects a diamond's brightness, brilliance, and dispersion. Any light-leakage caused by poor symmetry and/or cut proportions (off-make) will adversely affect the quality of light return.
Cut quality is divided into several grades listed below.
- Ideal Cut
- Premium Cut
- Very Good / Fine Cut
- Good Cut
- Fair Cut
- Poor Cut
CLARITY
All of the grades of diamond clarity reflect the appearance of inclusions within the stone when viewed from above at 10x magnification Higher magnifications and viewing from other angles are also used during the grading process. In "colorless" diamonds, darker inclusions will tend to create the most significant drop in clarity grade. In fancy-colored diamonds, light or pale inclusions may show greater relief, making them more apparent, causing a greater drop in grade.
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
COLOR
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 more yellow the stone will appear.
In determining the color rating of a diamond, the Gemological Institute of America uses a scale of "D" to "Z" in which "D" is totally colorless and "Z" is yellow.
Diamond Color Designations
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
CARAT
Balancing Cut and Weight
A diamond or gemstone's "Carat" designation is a measurement of both the size and weight of the stone. One "Carat" is a unit of mass that is equal to 0.2 grams (200 milligrams or 3.086 grains) or 0.007 ounce. 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."