Beverly Clark Diamonds Glossary

AGS (American Gem Society): An educational institution for gemological studies. The AGS Labs were created primarily to develop and promote universally accepted standards for grading cut.

AGS - American Gem Society:
Founded in 1934, this professional jeweler’s society has a laboratory which grades diamonds and offers diamond grading reports. AGS offers a cut grading system for round diamonds.

AGS Cut Grading Scale:
0: Ideal
1: Excellent
2: Very Good
3-4: Good
5-7: Fair
8-10: Poor

Appraisal:
An appraisal is a written estimate expressing the approximate retail replacement value of the appraised item. The appraisal is often used for insurance purposes and should generally by updated when other insurable items are reviewed.

Bezel facet:
Eight large triangular facets found on the crown of a round brilliant diamond. Also referred to as a top main facet.

Blemish:
Generally the result of environmental elements a diamond has encountered after being unearthed, a blemish is a characteristic of clarity that occurs on the surface of a diamond. Some blemishes are a natural occurrence of the original rough diamond.

Brilliance:
The term “brilliance” describes the reflective brightness of white light coming from the diamond. This reflective light occurs when light enters through the diamond’s table, reaches the pavilion facets, and is then reflected back out through the table.

Brilliant cut diamond:
This is a round diamond usually possessing 57 facets. Round brilliant cut diamonds present greater brilliance than other types of fancy-shaped cut diamonds. This type of cut is referred to as a brilliant cut because it is designed to maximize a diamond’s brilliance.

Carat:
The term refers to the unit of weight (in milligrams) used to measure a diamond. One carat is equal to 200 milligrams, or 0.2 grams.

Carbon Spots:
The term, often used inaccurately, describes inclusions, or included crystals, that present a dark appearance instead of a white or transparent appearance under a microscope. Generally, such dark inclusions are not visible to the naked eye, and will have little or no affect on the brilliance of the diamond.

Cavity:
A cavity refers to a type of inclusion formed by a deep or substantial opening in the diamond.

Clarity:
Clarity is measured on a scale ranging from Flawless (FL) to Imperfect (I) and refers to the degree to which a particular diamond is found to be free from inclusions.

Cleavage:
The natural characteristic of crystalline minerals, including diamonds, to split either along or parallel with, specific planes, when struck by a gem cutter. This is one of the two primary methods used by diamond cutters in the process of splitting rough diamond crystals as they are prepared for the refined cutting process.

Clouds:
Refers to a cluster of extremely small inclusions usually found to be to be indistinguishable from one another, even under high magnification. This results in a grouping that often appears as a wispy transparent cloud suspended within the diamond. Because it cannot be seen with the naked eye, this type of inclusion poses little or no significant effect on a diamond's clarity grade.

Color Grading:
A grading system used by the industry to grade diamond colors based (for white diamonds) on their colorlessness or (for fancy color diamonds), their spectral hue, depth of color and purity of color. GIA and AGS both utilize a grading system for white diamonds, which runs from “D” for “totally colorless” to “Z “representing a “light yellow.”

Crown:
The “crown”, which lies above the girdle, refers to the upper portion of a cut gemstone.

Crown angle:
The crown angle helps to enhance both the dispersion (or fire) in a diamond as well as a diamond’s brilliance. The crown angle is the angle at which a diamond's bezel facets (or, on emerald cuts, the row of concentric facets) intersect the girdle of the diamond. As white light enters the diamond at different angles it is dispersed into its spectral hues, creating a kaleidoscopic effect of colors within the diamond.

Crystal:
Where diamonds are concerned, a crystal is a type of inclusion created when a mineral deposit is encased inside the diamond as it is formed over time and under tremendous pressure.

Culet:
A cutlet is a very small, flat facet sometimes placed by diamond cutters at the bottom of a diamond's pavilion. The purpose of a cutlet is to protect the tip of the pavilion from being chipped or otherwise damaged. Generally, the setting into which a diamond is placed will provide appropriate protection for the pavilion from damage caused by impact or daily use. Most contemporary shapes will possess either a very small culet or no culet at all.

Cut:
“Cut” refers both to the overall proportions and finish of a polished diamond. Considered one of the industry’s “Four Cs" of diamond value, “cut” is the principal man-made contribution to a diamond's value and overall appeal.

Depth:
Measured in millimeters, “depth” represents the height of a diamond from the culet (or tip of the pavilion) to the table.

Depth Percentage:
A diamond grading report will show two different measurements of the diamond's depth. These two measurements will include the actual depth in millimeters (under "measurements", generally found at the top of the report) and the depth percentage, which defines the depth of a diamond divided by its average width. The importance of this depth percentage will depend on the diamond’s cut. As an illustration, a 75% or 78% depth for a princess cut diamond would be quite typical and considered to be attractive. On the other hand, a depth of even 65% would be considered detrimental to the beauty of a round cut diamond.

Diamond:
A very hard crystal consisting of 99.95% pure carbon with it’s atoms organized in an isometric, or cubic, crystalline arrangement. This unique structuring of the carbon atoms makes the diamond look and behave differently from all other pure carbon minerals such as the graphite that is found in pencils.

Diamond Cutting:
This is the primary method used to fashion a rough diamond into a finished, faceted gemstone.

Diamond Gauge:
The instrument used to measure a diamond's length, width and depth in millimeters is referred to as a diamond gauge.

Dispersion:
The bright, fiery, rainbow colors projected from a diamond, as white light is broken-up into its spectral colors when the light strikes the diamonds various facets.

EGL:
The European Gemological Laboratory, or EGL, grades diamonds and offers a diamond grading certificate through it worldwide network of franchises.

Emerald Cut:
This is a square or rectangular-shaped diamond with cut corners. The crown will display three concentric rows of facets arranged around the table and, on the pavilion, there will be three concentric rows arranged around the culet. Often referred to as a “Step Cut”, this cut displays broad, flat planes that can resemble stair steps.

Eye-Clean:
This is a jewelry industry term used to describe a diamond without blemishes or inclusions that would be visible to the naked eye without the use of a magnifying device such as a jeweler's loupe or a microscope.

Facet:
The smooth, flat faces on the surface of a diamond. The shape, quantity, and arrangement of these facets allow light to enter a diamond as well as reflect off of its surface at a variety of different angles.

Fancy Shape:
Any diamond shape other than a round shape.

Feather:
A small, fracture in a diamond that sometimes resembles a white feather.

Finish:
The “finish” represents the total sum of qualities given to a diamond at the hands of a skilled diamond cutter. The term "finish" covers every aspect of a diamond's appearance that is not a result of the diamond's inherent nature when it comes out of the ground. The crafting of the diamond's design, the exactitude found in the details of its cut combined with the overall quality of its polish are carefully considered by a gemologist in the process of grading “finish.” When examining a diamond's grading report, you will notice its “finish” will be graded according to two both “polish” and “symmetry.”

Fire:
The rainbow colors seen in a diamond as a result of dispersion that takes place when white light enters the diamond an is broken up into it’s spectral colors.

Fluorescence:
Some gem-quality diamonds display this effect when they are exposed to long-wave ultraviolet light. Generally not detectable under most lighting conditions, fluorescence will appear as a soft colored glow when a diamond possessing natural florescence is held under an ultraviolet lamp or "black light." This effect occurs naturally in many gems and minerals.

Fracture:
A chip or break on a diamond that doe not follow the direction of a cleavage plane. They are generally irregular in shape and may appear as step-like or a splinter.

Fracture filling:
A process used to enhance a diamond that involves filling a cavity in a diamond with some type of clear substance.

Gemological Institute of America (GIA):
GIA was founded in 1931 by Roger Shipley as a non- profit organization whose mission is to uphold the highest possible standards for the grading of diamonds and other precious gemstones. The GIA offers a highly respected gemological laboratory that is recognized worldwide for its excellence. GIA developed and standardized the diamond grading system that is used today by most legitimate gem labs.

Girdle:
This is the outer edge, or outline, of a diamond's shape. While the “girdle” is not graded, it is clearly described by its appearance at by its narrowest and widest points. Girdle thickness will be described as: extremely thin; thin; medium; slightly thick; thick; extremely thick.

Grading report:
Sometimes called a “certificate”, although labs do not “certify” diamonds. The grading report, issued by an independent laboratory, should accurately describe the proportions, weight, color, clarity, symmetry, polish and possible fluorescence seen in the diamond being evaluated. Some labs such as GIA and AGS are felt by many experts to be more consistent and stringent in their grading than some other labs.

International Gemological Institute (IGI):
IGI is one of several notable laboratories, which offers a grading report as well as written appraisals.

Inclusion:
An “inclusion” is a characteristic of the clarity to be found within a diamond. Most inclusions were created while the gem was first being formed deep inside the earth.

Laser drilling:
This is a technique used to enhance a diamond by drilling a tiny hole to an inclusion using a laser. The inclusion can then be bleached to enhance the diamond’s appearance.

Laser-drill holes:
This is an intentional, man-made inclusion that can be found inside some diamonds. Occasionally, the diamond cutter will make the decision to use a procedure to remove dark inclusions in order to increase the clarity of the diamond. An acid is then used to dissolve the inclusion while the surrounding diamond material remains unaffected. This process results in a more transparent diamond without compromising the diamond’s structural stability.

Length-to-width ratio:
A comparison of how much longer a diamond is than it is wide. It is used to analyze the outline of fancy shapes only; it is never applied to round diamonds. There is really no perfect or "ideal" ratio; it's more a matter of personal taste and aesthetic preferences. For example, while many people are told that a 2 to 1 ratio is best for a marquise; most people actually tend to prefer a ratio of around 1.80 to 1 when they actually look at marquises. And though the standard accepted range for the length-to- width ratio of a marquise generally falls between 1.70 to 1 and 2.05 to 1, there are customers who insist on having 'fatter' marquises of about 1.60 to 1 and other customers who want longer, thinner marquises of 2.25 to 1.

Length-to-width ratio:
This is a comparison of the total length and total width of the girdle outline of fancy-shaped diamonds and never for round diamonds. The ratio is determined by dividing the length of the diamond by the width. The width is always stated as 1. Some L to W ratios are considered to be more appealing than others, but this is a matter of personal preference.

Emerald
1.50 - 1.75 : 1
Heart
0.98 - 1.02 : 1
Marquise
1.75 - 2.25 : 1
Oval
1.33 - 1.66 : 1
Pear
1.50 - 1.75 : 1
Radiant/Princess
0.95 - 1.05 : 1

Loupe:
Sometimes referred to as a “jeweler’s loupe”, this small magnifying lens is used to examine diamonds and other gemstones. Generally, a 10x magnification is the standard.

Lower-girdle facet:
Located just below the girdle, these are the facets found on the pavilion of a round brilliant cut diamond.

Marquise Cut:
Considered as a “fancy shape” diamond, a “marquise” cut has an elongated shape with points at each end.

Mohs scale:
This is the 10-point scale by which mineral hardness is expressed. Diamond, being the hardest known natural substance for example, ranks a 10 on the Mohs Scale.

Naturals:
Generally undetectable without the aid of magnification, “naturals” are tiny remnants of the diamond's original rough surface, which remain on the polished diamond, often on or near the girdle. Despite the fact that “naturals” are blemishes, they can be regarded as a reflection of the skilled cutter's ability to craft a stunning polished gem, while at the same time preserving a portion of the original crystal's character and weight. The presence of naturals does not typically impact the clarity grade.

Old European cut diamond:
The name, which speaks for itself, represents the earliest known form of brilliant cut diamond presenting an extremely small table, heavy crown and great depth.

Oval Cut:
An “oval” cut diamond is part of the “fancy shape” group of diamonds and is, for all intents and purposes, an elongated version of a round cut.

Pavé:
This is a particular style of jewelry setting upon which many small diamonds are mounted very close together as a means of creating a twinkling diamond crust that essentially covers that portion of a piece of jewelry, obscuring the metal that comprises the setting.

Pavilion:
This is the total lower portion of the diamond found below the girdle.

Pavilion main facet:
These are the eight facets located on the pavilion of a round brilliant diamond with their points touching the girdle.

Pear Cut:
This is a cut in the “fancy shape” group of diamonds that resembles a teardrop.

Pinpoints:
These are very small inclusions in a diamond, which are generally not visible without the aid of magnification.

Point:
A “point” is a unit of measurement used as an expression of the weight of diamonds. One point is equivalent to 1/100th of a carat. As an example, a 1/4 carat diamond is described as weighing 25 points.

Polish:
Polish represents an indication of the quality of a diamond's cut and how the cutter has finished the facets on a diamond. Laboratories such as GIA will grade as either Ideal, Excellent, Very Good, Good, Fair or Poor based on the “polish” characteristics such as faint polishing lines and small surface nicks or scratches which are generally not significant enough to affect the clarity grade of the diamond.

Princess Cut:
This is a “fancy shape” brilliant cut diamond that can be either square or rectangular in shape.

Radiant Cut:
This “fancy shape” brilliant cut resembles a square or rectangle with the corners sliced off.

Ratio:
“Ratio”, as a comparison of a diamond’s length versus its width, is used to analyze the outline of fancy shapes only and is never applied to round cut diamonds.

Semi-mount:
This is a type of jewelry setting whereby the side stones are already mounted and the prongs intended for setting the center stone remain empty in order to allow for personalized selection of a diamond for that setting.

Shape:
Generally eight common diamond shapes are recognized: round, marquise, pear, oval, heart, princess/radiant, emerald, and trillion. The most popular shape is the “round” cut with the rest being considered “fancy-shaped.” There are other, less common shapes cut and marketed by a variety of manufacturers.

Single-cut:
This is a very small round diamond with only 16 or 17 facets, instead of the usual 57 or 58 facets required for a full cut round brilliant diamond. A typical use for “single cuts” would be for pavé jewelry or other styles of jewelry that cluster groups of petite diamonds to create a glittery, sparkle effect.

Star facet:
A “star facet” is one of the eight triangular facets located on the upper crown section of a brilliant-cut diamond.

Step Cut:
This version of the three standard styles of faceting arrangements possesses three concentric rows of facets arranged around the table along with three concentric rows arranged on the pavilion around the culet. The other two standard styles are the “brilliant” cut (where all the facets radiate outward from the center of the diamond) and the “mixed” cut (where the crown or pavilion of a diamond is a “brilliant” cut, and the other part of the diamond is cut as a “step” cut).

Symmetry:
Symmetry is considered to be an indicator of the quality of as diamond's cut and is graded by laboratories such as GIA either as: Ideal, Excellent, Very Good, Good, Fair or Poor. The term refers to variations in a diamond's symmetry that may include poorly aligned facets and/or facets that are not properly directed towards the girdle. Such minor misalignment is generally not visible without that aid of magnification.

Table:
The “table” is the flat facet (and generally a cut diamond’s largest facet) at the top of the diamond.

Table percentage:
For a round diamond, gemologists calculate table percentage by dividing the diameter of the table as measured in millimeters, by the average girdle diameter. This establishes the “table percentage” or how the diameter of the table facet compares to the diameter of the entire diamond.

Trilliant Cut:
A “trilliant cut” is a part of the brilliant fancy shape group of diamond cuts and has a triangular shape.