Diamond Information

It's All About Brilliance!! Just as color grading defines the degree of colorlessness and clarity grading defines the degree of flawlessness, cut grading addresses the degree of brilliance.

The 4 C’s of diamond grading are not four C’s at all but rather B followed by three C’s. The B stands for brilliance, the most important attribute of a gem grade diamond in that the beauty of a diamond is actually the beauty of the brilliance of light. Cut, the proportions and finish of a diamond, are what determine diamonds optical qualities and cut (brilliance) grading assesses the nature of those optical qualities that make up diamonds brilliance – the amount of light and the nature of and balance of light returned to the viewers eye. Brilliance (cut) is the most important consideration in the evaluation of gem grade diamonds, diamonds with color at J or above and clarity above SI–2. The brilliance (cut) of a diamond influences the diamonds value and price by as much as 25%. Yet is it the least documented or understood when purchasing a diamond.

In describing the make of a diamond two words are used, shape and cut. Shapes, such as round brilliants, emerald shapes, radiants, princess, pears, ovals, marquis and hearts indicate the overall appearance and faceting style of any one individual diamond. Cut grading of a diamond classifies the quality of any individual diamond shape by its proportions and finish, with each diamond shape having unique proportional and finish characteristics.

Proportions, the empirical data of degrees of angle, measurements and percentage of measurements, record the specific characteristics of each shape of diamond. For round diamonds all measurements are expressed in relation to that diamonds average diameter whereby a table measurement of 55% or a total depth measurement of 60% are expressions of their percentage of the averaged diameter of the diamond. Measurements for elongated diamond shapes such as emerald cuts, radiant cuts, and ovals are expressed as a percentage of the width alone. Degrees are used to measure the angle of the crown (top, above the girdle) and pavilion (bottom, below the girdle) of the diamond in relationship to the plane of the girdle (diameter). Finish is an interpretive observation of the quality of both the polish of a diamonds exterior surfaces and its symmetry, the relationship of one cutting feature to another, the alignment of the diamond. Each diamond shape is graded by the cut characteristics of its proportions and finish. Both the empirical data of the proportions and the interpretive observation of the finish are considered in a judgment of the overall cut grade assigned to a diamond.

It was the Gemological Institute of America that first developed a standardized grading system for round diamonds, classifying the empirical data and interpretive observations into four cut grades, those being Make Class One, Make Class Two, Make Class Three and Make Class Four. The American Gem Society has further refined the GIA grading system with strict definitions of variance for both the proportions and finish of a diamond in a system that rates diamond brilliance (cut) by variances from zero (ideal) to ten (poor). Today, the best system of brilliance (cut) grading for fancy shape diamonds (standard shapes other than round) is that of the Accredited Gem Appraisers and Mr. David Atlas, a system that rates diamonds into three general brilliance (cut) quality categories that are described as fine, average and below average.

Brilliance (cut) grading defines the quality of the optical properties of diamond as those optical properties relate to the light we perceive in viewing a diamond and as it is said, the beauty of diamond is, simply, the beauty of light. Just as color grading defines the degree of colorlessness and clarity grading defines the degree of flawlessness, cut grading addresses the degree of a diamonds brilliance. Once a diamonds clarity and color values are in the gem grades whereby there are no eye visible inclusions (flawlessness) and no apparent yellowing (colorlessness), the optical properties (brilliance) become the most important determinant of diamonds beauty. Stating that point at which a diamond becomes of gem grade is a value judgment unique to the experience and values of each individual gemologist with many feeling that for a one carat round brilliant cut diamond, the point on the GIA grading continuum at which such a diamond becomes of gem grade is J color and SI–2 clarity with Make Class Two cut.

Because a diamonds degree of brilliance is not as easily conceptualized as its color and clarity and because most sellers use spotlights to cheat (artificially enhance) cut quality you are in a buyer beware situation if you are not purchasing your diamond from a Graduate Gemologist who knows how to represent Cut (brilliance) properly. A precise representation of cut can only be achieved using technically advanced proportion grading instrumentation.

Flash, dispersion, blend and scintillation are properties of diamonds cut, the prime determinants of the light display produced by each diamond. Some diamonds are bright and dance with life whereas other diamonds are obscure, dull and lifeless. In that the beauty of diamond is the beauty of light, cut is the prime determinant of diamonds beauty in any given color or clarity grade.

As you can see diamond grading has several components for consideration. Whereas color grading relates to the continuum from colorlessness to yellow, clarity grading deals with the position, nature and size of inclusions and cut determines the flash, dispersion, blend and scintillation of light. Color is relatively easy to understand, followed by clarity and the visibility of inclusions (flaws). Cut on the other hand is more difficult for the mind to “picture” and therefore, although it is the single most important determinant of diamonds beauty it is the least understood quality component. The blame for this long accepted ignorance is in the retail jewelry industry because the retail jewelry industry has relied on professional salesmen rather than professional gemologists to demonstrate diamonds to the public. Further, retail jewelers have, for too long, used spotlights to demonstrate diamonds and those multi–directional spotlights can make a jelly glass sparkle. As the educational efforts of Gemological Institute of America are resulting in an industry wide class of professional gemologists, cut is beginning to be properly represented and is, slowly, gaining its preeminent position as the single most important attribute of diamonds beauty.

Elements of Brilliance (cut):

FLASH: The adamantine (hard due to molecular density) surface of a polished diamond provides for an optimal reflection of environmental light from diamonds exterior surfaces. The top of a diamond (crown) is composed of one large center facet, the table and bordered around by smaller crown facets. When the table is too large and/or the surrounding crown facets are too relatively small or their degree of angle is too steep, flash overpowers the appearance of refracted, prismatic fire light from within the diamond.

DISPERSION: The refracted colors of diamond light are the result of white light being bent, as it travels through the molecularly dense crystal structure, to reveal the component rainbow of colors that compose white light. When a diamond is cut too deep, increasing the degree of the pavilion (bottom) angle this prismatic light, diamonds fire, increasingly leaks out the sides of the diamond rather than being returned to the top (crown) and the viewers eye.

BLEND: The balance of flash and fire is a function of the depth and degree of angle of the pavilion and the height and degree of angle of the crown facets and the resulting size of the table (top center facet) of each diamond. Optimally we want to see an even blend of flash and refracted light across the entire field of vision of the crown of the diamond.

SCINTILLATION: The dance of twinkling light, optimally in an evenly distributed pattern across the field of vision of the crown of the diamond, is a function of the movement of the diamond and/or the movement of the viewer as light plays from one exterior and/or interior facet to another.

BRILLIANCE: The total effect of flash, dispersion, blend and scintillation are the component parts of a diamond’s brilliance.
You must know the diamond's true proportions to make an objective assessment of cut:

– Depth and pavilion angle guides our understanding of the total amount of refracted light (fire) within the diamond that is returned to the eye.

– Table percentage and crown angle guides our understanding of the blend of environmental light (flash) from the exterior crown facets and fire from within the diamond.

– The girdle is the critical interface between diamond crystal and the jewelry mounting and is the most carat intensive portion of the diamond.

– The polish and symmetry grades disclose the care with which the blocker and brillianteer have crafted each diamond.

Each shape of a diamond, be it round, emerald cut, pear, princess, oval, heart or marquis has its own unique set of proportional values that determine the brilliance of diamonds in that shape. And finally, we have seen the diamond grading contributions of the leading experts in the field, including Mr. David Atlas and associates of The Accredited Gem Appraisers, The Gemological Institute of America and The American Gem Society and International Gemological Institute. Diamonds are widely studied with diamond grading research being ever improved by the contributions these professional men, and women.