Baguette: A step cut in the shape of a small rectangular stone. May be tapered at one end.

Bearded girdle: Tiny, numerous, hair like fractures extending into the stone.

Bezel:A facet on the Crown, or upper part of the Diamond above the Girdle.

Blemish: A clarity characteristic that occurs on the surface of a diamond. Though some blemishes are inherent to the original rough diamond, most are the result of the environment the diamond has encountered since it was unearthed.

Brilliance: The brightness that seems to come from the very heart of a diamond. It is the effect that makes diamonds unique among all other gemstones. While other gemstones also display brilliance, none have the power to equal the extent of diamond's light-reflecting power. Brilliance is created primarily when light enters through the table, reaches the pavilion facets, and is then reflected back out through the table, where the light is most visible to your eye.

Brilliant Cut: One of three styles of faceting arrangements. In this type of arrangement, all facets appear to radiate out from the center of the diamond toward its outer edges. It is called a brilliant cut because it designed to maximize brilliance. Round diamonds, ovals, radiant, princesses, hearts, marquises, and pears all fall within this category of cut. Other styles of faceting arrangements include the step cut (in which facets are arranged in concentric rows around the table and the culet) and the mixed cut (in which either the crown or pavilion of a diamond is cut as a brilliant cut, and the other part of the diamond is cut as a step cut). Note: Some jewelers use the term "Brilliant cut" as a synonym for "round diamond."

Bort: Industrial grade diamonds Bow-Tie Effect: An effect caused by a shadowy area visible in some fancy shapes, caused by light leaking out the bottom of the Diamond.

Bruise: An inclusions consisting of surface crumbling, often accompanied by tiny, root like feathers.

Burned Facet: This facet may appear whitish, or burnt, as a result of the cutter polishing the facet "against the grain".

Carat Weight: The metric carat, which equals 0.200 gram, is the standard unit of weight for diamonds and most other gems. If other factors are equal, the more a stone weighs, the more valuable it will be.

Carbon Spots: An inaccurate term used by some people in the jewelry industry to describe the appearance of certain inclusions in a diamond. The term refers to included crystals that have a dark appearance, rather than a white or transparent appearance, when viewed under a microscope. In most cases, these dark inclusions are not visible to the naked eye, and do not affect the brilliance of the diamond.

Cavity: An inclusion consisting of a large or deep opening in the stone.

Chip: A tiny piece missing, caused by normal wear and tear, or by cutting.

Clarity: A stone'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 determine the clarity grade. Very few diamonds are flawless, that is, show no inclusions or blemishes when examined by a skilled grader under 10X magnification. If other factors are equal, flawless stones are most valuable.

Cleavage: The propensity of crystalline minerals, such as diamond, to split in one or more directions either along or parallel to certain planes, when struck by a blow. Cleavage is one of the two methods used by diamond cutters to split rough diamond crystals in preparation for the cutting process (sawing is the other method).

Cloud: A group of tiny white inclusions which result in a milky or cloudy appearance.

Coated Diamond: A diamond colored by a surface coating which masks the true body-color; the coating may be extensive (entire pavilion, for example), but is more often limited to one or two pavilion facets or a spot on the girdle.

Color: Grading color in the normal range involves deciding how closely a stone's body color approaches 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 the most valuable.

Crown: The upper part of the diamond above the girdle. Consists of a large flat area on top called a table, and several facets below it. Culet: The smallest facet at the bottom of the diamond.

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

Culet: A tiny flat facet that diamond cutters sometimes add at the bottom of a diamond's pavilion. Its purpose is to protect the tip of the pavilion from being chipped or damaged. Once a diamond is set in jewelry, though, the setting itself generally provides the pavilion with sufficient protection from impact or wear. Large or extremely large culets were common in diamonds cut in the early part of this century, such as the Old European or Old Mine Cut. However, such large culets are rarely seen today. Most modern shapes have either no culet at all, or a small or very small culet.

Cut:The proportions and finish of a polished diamond (also called make). Cut can also mean shape, as in emerald cut or marquise cut. Proportions are the size and angle relationships between the facets and different parts of the stone. Finish includes polish and details of facet shape and placement. Cut affects both the weight yield from rough and the optical efficiency of the polished stone; the more successful the cutter is in balancing these considerations, the more valuable the stone will be.

Depth: The height of a diamond from the culet to the table. The depth is measured in millimeters.

Depth Percentage: On a diamond grading report, you will see two different measurements of the diamond's depth-the actual depth in millimeters (under "measurements" at the top of the report) and the depth percentage, which expresses how deep the diamond is in comparison to how wide it is. This depth percentage of a diamond is important to its brilliance and value, but it only tells part of the story. Where that depth lies is equally important to the diamond's beauty; specifically, the pavilion should be just deep enough to allow light to bounce around inside the diamond and be reflecting out to the eye at the proper angle. Keep in mind, also, that a depth percentage that might be excessive for one diamond cut might be necessary for another type of cut. For example, a 75% or 78% depth in a princess cut diamond would be typical and quite attractive. However, a depth of even 65% would be unnecessary and even detrimental to a round diamond's beauty.

Diamond: A crystal made up of 99.95% pure carbon atoms arranged in an isometric, or cubic, crystal arrangement. It is this unique arrangement of the carbon atoms that makes diamond look and behave differently from other pure carbon minerals such as graphite (the soft black material used to make pencils).

Diamond Cutting: The method by which a rough diamond that has been mined from the earth is shaped into a finished, faceted stone. As a first step, cleaving or sawing is often used to separate the rough into smaller, more workable pieces that will each eventually become an individual polished gem. Next, bruiting grinds away the edges, providing the outline shape (for example, heart, oval or round) for the gem. Faceting is done in two steps: during blocking, the table, culet, bezel and pavilion main facets are cut; afterward, the star, upper girdle and lower girdle facets are added. Once the fully faceted diamond has been inspected and improved, it is boiled in hydrochloric and sulfuric acids to remove dust and oil. The diamond is then considered a finished, polished gem.

Diamond Gauge: An instrument that is used to measure a diamond's length, width and depth in millimeters.

Facet: The smooth, flat faces on the surface of a diamond. They allow light to both enter a diamond and reflect off its surface at different angles, creating the wonderful play of color and light for which diamonds are famous. The table below shows all the facets on a round brilliant cut diamond. A round brilliant has 58 facets (or 57 if there is no culet).

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

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

Feathers: These are small fractures in a diamond. They are usually caused by the tremendous stress that the diamond suffered while it was growing underground. In some cases the feather both begins and ends within the diamond's surface and, in other cases, the feather begins inside the diamond and extends to the surface. When viewed under magnification, some feathers are transparent and others have a light white appearance to them. The term "feather" comes from the fact that, under magnification, these fractures often seem to have an indistinct, feathery shape to them. While the idea of buying a diamond with "fractures" may sound scary, the reality is that, with normal wear and care, most feathers pose no risk to the diamond's stability. Consider this: even with the feathers, these diamonds survived their growth and their journey to the surface intact. Once on the surface, they also survived the mining process, as well as the brutal stresses of the diamond cutting process. Though diamonds are certainly not invulnerable to damage, basic consideration to their care and handling during everyday wear will most likely protect them over the course of several human lifetimes.

Flaw: An imperfection of a stone.

Fracture: A crack on the Diamond's surface.

Finish: This term refers to the qualities imparted to a diamond by the skill of the 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 execution of the diamond's design, the precision of its cutting details, and the quality of its polish are all a consideration when a gemologist is grading finish. If you examine a diamond's grading report, you will see its finish graded according to two separate categories: polish and symmetry.

Fluorescence: An effect that is seen in some gem-quality diamonds when they are exposed to long-wave ultraviolet light (such as the lighting frequently seen in dance clubs). Under most lighting conditions, this fluorescence is not detectable to the eye. However, if a diamond is naturally fluorescent, it will emit a soft colored glow when held under an ultraviolet lamp or "black light." Fluorescence is not dangerous to the diamond or to the wearer; it is a unique and fascinating quality that occurs naturally in a number of gems and minerals. For additional information on the nature of fluorescence and its effect on diamonds.

Gemological Institute of America (GIA): Founded in 1931 by Roger Shipley, this non-profit organization upholds the highest standards for grading diamonds and other precious gems. The GIA has one of the most-respected and well-regarded gemological laboratories in the world; GIA was responsible for developing and standardizing the diamond grading system that is used today by nearly all other gem labs.

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

Grain Center: A small area of concentrated crystal structure distortion, usually associated with pinpoints.

Hardness: Mineral's resistance to scratching on a smooth surface. Mohs scale of relative hardness consists of 10 minerals, each scratching all those below it in scale and being scratched by all those above it.

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

Included Crystal: A mineral crystal contained in a diamond. Inclusion: Imperfection internal to the Diamond.

Inclusion: A clarity characteristic found within a diamond. Most inclusions were created when the gem first formed in the earth.

Internal Graining: Internal indications of irregular crystal growth. May appear milky, like faint lines or streaks, or may be colored or reflective.

Irradiated Diamond: A diamond which has been exposed to radiation.

Knot: An included diamond crystal which reaches the surface of a polished diamond.

Laser-Drill Holes: One of the few man-made inclusions that can occur inside a diamond. Why on earth would anyone want to drill holes into a perfectly good diamond? It may seem counter-intuitive, but drilling this type of hole into a diamond can actually raise its clarity grade. In some diamonds, the clarity grade may be determined mainly by the presence of just one or two dark included crystals in a diamond that is otherwise relatively free of inclusions. In certain circumstances, the diamond cutter will decide to use a procedure to remove the dark inclusions and, hopefully, increase the clarity of the diamond.

Loupe: Magnifying glass usually of 10X.

Melee: Small Diamonds under .20 carat.

Mohs scale: The ten-point scale of mineral hardness, keyed arbitrarily to the minerals talc, gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, corundum, and diamond.

Naturals: Small parts of the original rough diamond's surface which are left on the polished diamond, frequently on or near the girdle. While these are blemishes, they 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. In most cases, they are undetectable to the naked eye. Another type of natural is the Indented Natural; in this case, the portion of the original rough diamond's surface which is left on the polished diamond dips slightly inward, creating an indentation. Usually, the cutter makes an effort to cut the polished diamond so that the indented natural will be confined to either the girdle or the pavilion (making it undetectable to the naked eye in the face-up position).

Needle: A long, thin included crystal which looks like a tiny rod.

Nick: A notch near the girdle or a facet edge.

Off-Make: A poorly proportioned Diamond.

Pavé: A style of jewelry setting in which numerous small diamonds are mounted close together to create a glistening diamond crust that covers the whole piece of jewelry and obscures the metal under it.

Pavilion: The bottom part of the Diamond, below the girdle.

Pinpoints: Miniscule spots internal to a Diamond. A cluster of pinpoints can form a cloud.

Pit: A tiny opening, often looking like a white dot.

Point: A unit of measurement used to describe the weight of diamonds. One point is equivalent to one-hundredth of a carat.

Polish: Refers to any blemishes on the surface of the diamond which are not significant enough to affect the clarity grade of the diamond. Examples of blemishes that might be considered as 'polish' characteristics are faint polishing lines and small surface nicks or scratches. Polish is regarded as an indicator of the quality of as diamond's cut; it is graded as either Ideal, Excellent, Very Good, Good, Fair or Poor.

Polish Mark: Surface clouding caused by excessive heat (also called burn mark, or burned facet), or uneven polished surface resulting from structural irregularities.

Rough Girdle: A grainy or pitted girdle surface, often with nicks.

Round Brilliant cut: The most common cut containing 58 facets. Also the most brilliant cut, in terms of most efficient use of light to increase brilliance and fire, hence the name.

Saturation: A color's position on a neutral to vivid scale.

Semi-mount: A jewelry setting that has the side stones already mounted, but which contains an empty set of prongs which are intended to mount a diamond center stone that the customer selects separately.

Scratch: A linear indentation normally seen as a fine white line, curved or straight.

Single-cut: A very small round diamond with only 16 or 17 facets, instead of the normal 57 or 58 facets of a full cut round brilliant. Single cuts are occasionally used for pavé jewelry and other jewelry that utilizes numerous small diamonds set closely together.

Step Cut: One of three styles of faceting arrangements. In this type of arrangement (named because its broad, flat planes resemble stair steps), there are three concentric rows of facets arranged around the table and, on the pavilion, there are three concentric rows arranged around the culet. Other styles of faceting arrangements include the brilliant cut (in which all facets radiate out from the center of the diamond toward its outer edges) and the mixed cut (in which either the crown or pavilion of a diamond is cut as a brilliant cut, and the other part of the diamond is cut as a step cut).

Symmetry: Refers to variations in a diamond's symmetry. The small variations can include misalignment of facets or facets that fail to point correctly to the girdle (this misalignment is completely undetectable to the naked eye). Symmetry is regarded as an indicator of the quality of as diamond's cut; it is graded as either Ideal, Excellent, Very Good, Good, Fair or Poor.

Spread stone: A Diamond with a large table and a thin crown height.

Surface Graining: Surface indication of structural irregularity. May resemble faint facet junction lines, or cause a grooved or wavy surface, often cross facet junctions.

Table: The flat facet on the top of the diamond. It is the largest facet on a cut diamond.

Table percentage: The value which represents how the diameter of the table facet compares to the diameter of the entire diamond. So, a diamond with a 60% table has a table which is 60% as wide as the diamond's outline. For a round diamond, gemologists calculate table percentage by dividing the diameter of the table, which is measured in millimeters (this millimeter measurement does not appear on diamond grading reports) by the average girdle diameter (an average of the first two millimeter measurements on the top left-hand side of a diamond grading report). For a fancy shape diamond, table percentage is calculated by dividing the width of the table, at the widest part of the diamond, by the millimeter width of the entire stone (this total width measurement is the second of the three millimeter values in the top left-hand corner of the diamond grading report. Contrary to popular misconception, having a small table percentage (53% to 57%) does not make a round diamond any more brilliant than a diamond with a larger table.

Tone: A color's position on a colorless-to-black scale.

Treated Diamonds: A diamond with a body color induced by some form of artificial irradiation, often in conjunction with controlled heating (known as annealing).