The standard unit of weight for diamond and gems is the metric carat which equals to .20 gram. A 1 carat diamond consists of 100 points. Diamonds weighing less than a carat are referred to in "points". Thus a .90 carat diamond would be a .90 pointer
Found at the top of the Lab Grading Report. On the GIA Report it is on the upper left-hand margin in the vertical position.
Diamond Clarity grades range from the high of Flawless ( no impefections inside or outside the stone) to the Imperfect range (I-1, I-2, I-3) where inclusions may or may not be readily visible to the eye without magnification depending on the diamond's Cut quality.
VVS-1 and VVS-2 clarity usually consists of a microscopic pinpoint(s) that are visible only at very high 60X + magnification. VS-1 and VS-2 clarity grades may have either very small white, grey, or black feathers, carbon spots, or pinpoints, or any combination thereof. These inclusions can be seen with 10X magnification but the diamond will face-up eye-clean. Visibility of inclusions in SI-1 and SI-2 clarity diamonds will depend on their location, color, and size and on the cut quality of the stone.
The Diamond's Clarity Characteristics pertaining to the location, size, and color of inclusion(s)as determined and graded by GIA.
Diamond color grading in the normal range is to determine how closely a diamond's body color will approach colorlessness. Many diamonds have traces of yellow or brown body color. The colorless grade(s) range from the high of D down to L. D-E-F are considered colorless. G-H-I-J, near colorless. K-L-M, a tinge of faint yellow.
The visual detection of colorlessness or color is critically dependent on the diamond's Cut. The better the cut of the diamond, the greater the intensity and even distribution of light across the entire surface of the stone and thus a 'whiter' and greater colorless appearence.
The angle at which the Crown facets are polished.
The slope or height of the Crown Facet which will extend from the Table edge down to the Girdle.
The Culet is the pointed facet at the bottom of the diamond where all eight Pavillion facets merge. This facet prevents any of the Pavillion facets from chipping.
Of the Jeweler's 4 C's, the 5th C, that of "Cut" is the most important and critically impacts the beauty and light performance of the diamond. It is the only "C" that is controlled by Man. The diamond cutter's expertise in fashioning the facet angle, facet size, and facet alignment and placement determines the amount and intensity of reflected and refracted light and thus the diamond's light performance and beauty.
The depth percentage of the diamond is the distance of the table to culet relative to the width of the stone.
Fluorescence or "Blue-White" refers to the Diamond's reaction and visual appearence to long-wave ultraviolet radiation.
Fluorescence may be Blue, Yellow, or White. In less than 1% of polished diamonds, will Fluorescence impart an oily, hazy, or opaque appearence to the diamond which is readily noticeable.
In I-J-K colors, Fluorescence will make the diamonds appear whiter in the face-up position. In the colorless range of D-H, Fluorescence will give off a pleasing blue-white glow in direct sunlight.
The Girdle of the Diamond is the dividing line between the top of the diamond, referred to as the Crown, and the bottom of the Diamond referrred to as the Pavillion. The girdle may or may not be faceted and the thickness of the girdle is usually expressed as a range from minimum to maximum. The majority of the Diamond's girdle will fall between these two indicators.
Lab Reports issue three number measurements for the diamond. In Round brilliant shapes, the first two numbers are the maximum and minimum values of the diamond's diameter and the third number is the height which extends from the table (top of the stone) to the culet (pointed facet located at the bottom of the stone where all of the eight pavillion main facets converge).
In Fancy shapes, the first two numbers indicate the length and width and the third number indicates the height as in the round brilliant.
The angle at which the Pavillion facet is polished.
The slope of the Pavillion Facet that extends from the Girdle down to the Culet.
Diamond Polish refers to the quality of the Diamond's finish. All facets should be finished to a high gloss and sheen so that reflected and refracted light from the properly aligned facets will be maximized and evenly distributed across the entire surface of the diamond.
Diamond Price is determined by the 5 C's with Cut the most important as well as supply-demand for the particular carat weight, color, and clarity combination you're looking for.
Traditional Diamond Shapes are the Round Brilliant, Oval, Pear, Marquise, Emerald, and Princess.
Symmetry refers to the loose diamonds facet alignment. There are two kinds of Symmetry; external and internal. External Symmetry as seen on the GIA Report refers to the meet points of the Crown facets to the Pavillion facets. GIA will grade Symmetry as either Fair, Good, Very Good, and Excellent. The difference between Good to Excellent Symmetry is only visible under high magnification but undetectable to the eye. Internal Symmetry refers to Optical Symmetry, aka Light Performance which we measure with the Brilliancescope and Imagescope. Maximizing
Optical Symmetry and Light Performance entails the proper alignment and positioning of all the diamond's facets so that they act as mirrors to reflect and refract light with high intensity and even distribution. It is quite possible to maximize Light Performance and Optical Internal Symmetry even though the External Symmetry will show Good to Very Good. The converse is also true; Excellent External Symmetry does not necessarily indicate excellent Internal Optical Symmetry.
Table Percentage is the table size expressed as a percentage of the Diamond's average width.
