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Diamond Glossary

A

Abrasion - small imperfections along the facet junctions that produce a hazy line versus the desired sharp edging.

AGS - American Gem Society. As the center for gemological research the AGS Labs serve as the industry standard in evaluating the cut of a diamond.


B

Bezel - a facet located on the crown or in the upper portion of the diamond above the girdle.

Blemish - a clarity discrepancy that occurs on the surface of a diamond which, in turn, showcases an imperfection on the face of the diamond to the naked eye.

Bow Tie Effect - an effect caused by a shadowy area visible in the more intricate of diamond shapes that is caused by light leaking from the bottom of the diamond.

Brilliance – the brightness in a diamond represents the glow that comes naturally from the refracted light developed from the facets within the stone. This glow is unparalleled in any other stone typology.

Bruise - an inclusion consisting of surface crumbling, often accompanied by tiny, root like feathers.


C

Carat Weight - The metric carat, which equals 2 milligrams, represents the standard unit of weight for diamonds and most other types of gemstones. If all other factors in a diamond's quality are equal, the higher stone weight will yield a higher value.

Cavity - An inclusion consisting of a large or deep opening within the diamond.

Certificate - Laminated document by a gemological institute that outlines the specific attributes of a particular diamond.

Chip - A tiny piece missing from the stone caused by normal wear and tear or forced abrasion.

Clarity - A diamond's relative position on a flawless to imperfect scale. Clarity characteristics are classified as inclusions (internal) or blemishes (external). The size, number, position, nature, and color or relief of characteristics determines the clarity grade. Few diamonds exist that are perfectly flawless, meaning that the diamond shows no indication of inclusions or blemishes when examined by a skilled grader under 10X magnification. If all other factors in a diamond's quality are equal, flawless stones are the most valuable.

Cloud - A group of tiny white inclusions that result in a milky or cloudy appearance.

Color - Grading color involves deciding how closely the inherent color of a diamond iswith relation to colorlessness. Most diamonds have at least a trace of yellow or brown body color. With the exception of some natural fancy colors, such as blue, pink, purple, or red, the colorless grade is considered the most valuable.

Crown - The upper part of the diamond above the girdle that consists of a large flat area on top called a table and includes the several facets directly below.

Crown Angle - The angle upon which a diamond's bezel facets (or, on emerald cuts, the row of concentric facets) intersect the girdle plane. This gentle sloping of the facets that surround the table is what helps to create the dispersion within a diamond. White light entering at the different angles is broken up into a series of spectral hues, creating a beautiful play of color within the diamond itself. The crown angle also helps to enhance the brilliance of a diamond.

Culet - The smallest facet at the bottom of the diamond.

Cut - The proportions and finish of a polished diamond. Cut can also refer to the shape itself, as in emerald cut or marquise cut. Proportions relate to the size and angle relationships between the facets and different portions of the diamond. Finish includes the polish and detail of the facet shapes and placement. The cut affects both the weight yield from rough and the optical efficiency of the polished diamond.


D

Depth - The height of a diamond taken from the culet to the table measured in millimeters.

Depth Percentage - There are two different measurements of a diamond's depth - actual depth in millimeters and depth percentage, a factor which expresses how deep the diamond is in comparison to its width.

Diamond - A crystalline stone made up of 99.95% pure carbon atoms arranged in an isometric crystal arrangement. This unique arrangement of carbon atoms makes the diamond look and behave differently from other pure carbon minerals such as graphite.


E

Emerald Cut - A step cut, typically rectangular.

Excellent Cut - A GIA and HRD-CGL grade for excellent cut and polish of brilliants.

Extra Facet - A facet placed without regard for symmetry and not required by the cutting style.

Eye-Clean - A term used in the jewelry industry to describe a diamond without blemishes or inclusions that are visible to the naked eye.


F

Facet - Plane, polished surface of a diamond.

Faceted Girdle - Sometimes cutters polish the girdle into 32 facets.

Fancy Diamond - A diamond with an inherent natural body color other than light yellow or light brown.

Feather - A separation or break due to either cleavage or fracture, often white and fragmented in appearance.

Flaw - A typical imperfection within a diamond.

Fluorescence - The mostly bluish glow of a diamond in high ultraviolet lighting conditions. Ratings: none, faint, slight, medium, strong blue. Strong blue fluorescence may result in a diamond appearing oily or milky when in daylight.

Fracture - A crack on the diamond's surface.


G

GIA - Gemological Institute of America. This institute provides reliable diamond grading reports.

Girdle - The outer edge or the widest part of the stone forming a unified band around the diamond.

Grain Center - A small area of concentrated crystal structure distortion that is typically associated with pinpoints.


H

Hue - Pure, spectral (prismatic) color. Hues include gradations and mixtures of red, organge, yellow, green, blue, violet and purple tones.


I

Included Crystal - A mineral crystal contained within a diamond.

Inclusion - An imperfection internal to the diamond.

Internal Graining - Internal indications of irregular crystal growth. May appear milky, as faint lines or streaks, or may be colored and/or reflective.


L

Loupe - Magnifying glass usually of 10X.


M

Marquise Cut - A type of fancy shape diamond elongated to a point at each end.


N

Naturals - Small parts of the original rough stone's surface left on the polished diamond, frequently located on or near the girdle. While characterized as blemishes, these might also be regarded as a sign of skilled cutting; the presence of a natural reflects the cutter's ability to design a beautiful polished gem, while still retaining as much of the original crystal's weight as possible. In many cases, naturals do not affect the clarity grade and they are typically unnoticeable to the naked eye.

Needle - A long, thin included crystal that looks like a tiny rod.


O

Oval Cut - A type of fancy shape diamond, which is essentially an elongated version of a round cut.


P

Pavilion - The bottom portion of a diamondlocated below the girdle.

Pear Cut - A type of fancy shape diamond that closely resembles a teardrop.

Pinpoints - Very small imperfections that are internal to a diamond. A cluster of pinpoints can form a cloud.

Pit - A tiny opening, often appearing as a white dot.

Point - 100th of a carat.

Polish Lines - Tiny parallel lines left over from the polishing process. Fine parallel ridges confined to a single facet, caused by crystal structure irregularities, or tiny parallel polished grooves produced by irregularities in the scrape surface.

Polish Mark - Surface clouding caused by exposure to excessive heat or an unevenly polished surface resulting from structural irregularities.

Princess Cut - A type of brilliant cut fancy shape that can be either square or rectangular.


R

Radiant Cut - A type of brilliant cut fancy shape that resembles a square or rectangle with the corners cut off.


S

Surface Graining - Surface indication of structural irregularity that often resemblesa faint set of facet junction lines, or cause a grooved or wavy surface, often cross facet junctions.

Symmetry - Refers to variations within a diamond's symmetry. The small variations can include misalignment of facets or facets that fail to point correctly to the girdle. Symmetry is regarded as an indicator of the quality of a diamond's cut; it is graded as Ideal, Excellent, Very Good, Good, Fair or Poor.


T

Table - The flat faceting along the top of the diamond. It is the largest facet on a cut diamond.

Table Percentage - The quantitative value that represents how the diameter of the table facet compares to the diameter of the entire diamond.

Trillion Cut - A type of brilliant fancy shape that is triangular.