Diamond Cut Grading

What makes one diamond sparkle while another looks lifeless and dull? A good diamond is dazzling, romantic and priced according to quality. The most important factor is the grading and evaluation of a diamond’s cut. The purpose of this lesson is to provide a basic understanding of the evaluation of cut and proportioning and how it impacts a diamond’s beauty and value.

A properly cut diamond is proportioned so that no matter where light enters the stone... the light is directed out the top of the stone. This is difficult to achieve, but mathematically possible. The reason is that a diamond is cut to capture light entering it from a 360-degree sphere.

Deep Cut Diamond - A stone is cut too deep and the light is not being controlled to go out the top. Some diamonds are cut to have maximum weight rather than maximum beauty. Diamonds cut too deep retain weight, not beauty.

Shallow Cut Diamond - Looking from the top, it appears to be much larger than it really is. This is called a "fish-eye" or sometimes a "swindle cut," so-called because you can take a diamond of .80ct with this type of spread cut and make it appear as a 1.00ct diamond. Some people are fooled into thinking that they are getting a larger diamond for the money.

Ideal Cut Diamond - Light is coming in the top, traveling around the diamond interior and exiting out the top of the stone. No matter where the light enters this diamond, the light will go out the top. This is a brilliant and beautiful stone. Ideal cut diamonds are always more beautiful!

Diamond Color Grading

Color is the second most significant grading aspect of buying or selling diamonds. Diamonds are graded based on their overall body color, on a scale developed by the GIA. This scale runs from "D" to "Z". Note in the charts below how the difference between any two colors can be very subtle.

To achieve the highest degree of accuracy, diamonds must be color graded loose and with the proper equipment. The stones should be upside down to provide the best viewing of the crystal color, and a proper "North Light" source should be employed. Any diamond grade offered while a stone is still in its mounting should be noted as provisional, based on the limitations of grading a mounted diamond.

Colors D, E, F - The D-E-F colors are known as the colorless grades. Grade "D" is reserved for larger diamonds whose colors can be more accurately graded due to their size. Diamonds less than .50 carats usually receive a top grade of "F" due to the greater difficulty of precisely grading a small diamond.

Colors G, H, I - These are known as the "face white" or "face up colorless" grades because they appear colorless when viewed through the "face-up" position or through the table but show a slight tint of color when turned upside down for proper grading. This is due to the brilliance of the stone masking this very slight tint when viewed through the table.

Colors J, K, L - This grading range offers some nice diamonds if they are proportioned properly. A well-cut diamond of the K-L color range will still appear mostly colorless and can save you a good deal of money over a color grade of a higher range. Again, the cut is the key to keeping the stones of slight tint beautiful.

Colors M to Z - The lower colors "M" through "Z" have an increasing amount of yellow tint, ranging through the off colors and ending at the end of the scale, beyond which diamonds are considered to have a fancy yellow color. Be wary of jewelers offering fancy yellow-colored diamonds, however. Sometimes they grade off-color yellows as fancies without a proper gemological evaluation by a recognized gemological laboratory. The term fancy besides any diamond color imparts a higher value and higher price to the stone. Do not accept the term fancy for any diamond you purchase unless it is accompanied by an origin of color report and a diamond grading report from a recognized gemological lab that identifies the stone as being of natural color origin and truly fancy in color.

Diamond Clarity Grading

The least important diamond grade is clarity. Unfortunately, it is what many jewelers claim is most important, because it is the easiest to demonstrate. Anyone can put a diamond under a microscope and see if it has inclusions. It takes gemological knowledge to cut and/or color grade a diamond. Jewelry merchants with little or no formal gemology training often resort to a quick demonstration of clarity, which has made it the most important grade too many consumers. This could not be further from the truth.

By definition, any grade diamond of SI2 and above requires magnification to see the inclusion. How often do your friends look at your diamond under a loupe? Since any diamond of SI2 clarity and up is considered "eye clean," meaning you must have magnification to see any inclusion, why worry about clarity above the SI2 range? Of course, if you are told you are getting a VS1 you want make sure you actually are. But you can save lots of money by buying a diamond that is well proportioned, with good color, but is in the SI1 or SI2 clarity range. To put it another way, a perfectly cut diamond of D color and SI2 clarity will look the same to everyone around you as a perfectly cut diamond of D color VS1. However, the SI2 diamond could save you thousands of dollars.

FLAWLESS GRADE - No inclusions visible using 10x magnification.

VVS1 Grade - One tiny inclusion on the very upper outer edge of the diamond.

VVS2 Grade - Additional pinpoint inclusion but still on the outer perimeter of the diamond.

VS1 Grade - Small pinpoint and small feather on the outer edge of the diamond.

VS2 Grade - Small cloud of pinpoints and small feather, all on the outer edge.

SI1 Grade - A larger cloud of pinpoint inclusions and feather on the outer edge.

SI2 Grade - Cloud of inclusions, feather, and small feather located in the table of stone.

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