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As you shop for jewelry, especially diamonds, you may encounter some technical or unfamiliar terms. This glossary will help you understand some common jewelry terms. A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Abrasion - Small nicks along facet junctions that result in white, fuzzy lines instead of sharp facet edges. AGS (American Gem Society) - An educational organization for gemological studies. The AGS Labs were formed to develop and uphold universally accepted standards for grading cut. Bezel - A facet on the crown, or upper part of the diamond, above the girdle. Blemish - An imperfection on the diamond's surface. Bow Tie Effect - A shadowy area visible in some fancy shapes of diamonds caused by light escaping through the bottom of the diamond. Brilliance - The brightness that emanates from a diamond's center, which is caused by light refraction. Of all gemstones, diamonds have the most brilliance. Bruise - An inclusion, or flaw, comprised of surface crumbling and tiny, root-like feathers. Carat Weight - The metric carat, which equals 2 milligram, is the standard unit of weight for diamonds and most other gems. If other factors are equal, the more a diamond weighs, the more valuable it will be. Cavity - An inclusion, or flaw, consisting of a large or deep opening in the diamond. Certificate - Approved document from a gemological institute to describe and authenticate a diamond's characteristics. Chip - A tiny fragment missing, usually caused by normal wear or by cutting. Clarity - A diamond's rating scale ranging from flawless to imperfect. 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. Very few diamonds are flawless when examined under 10X magnification. If other factors are equal, flawless diamonds are most valuable. Cloud - A group of tiny white inclusions that make a gem appear milky or cloudy. Color - How closely a diamond's body color approaches clear. Most diamonds have at least a trace of yellow or brown body color. With the exception of some natural fancy colors, the colorless grade is the most valuable. Crown - The upper part of the diamond above the girdle, consisting of a large flat area on top and several facets below it. 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 light dispersion in a diamond. White light entering at the different angles fragments into its spectral hues, creating a beautiful color display and enhancing the diamond’s brilliance. Culet - The smallest facet at the diamond's bottom. Cut - The diamond's proportions and finish. Cut also refers to shape, such as emerald cut or marquise cut. Proportions are the size and angle relationships between the facets and different parts of the diamond. Finish includes polish and details of facet shape and placement. Cut affects the diamond’s size and its brilliance. Depth - The height of a diamond from the culet to the table, measured in millimeters. Depth Percentage - How deep the diamond is in comparison to how wide it is. Diamond - The hardest natural substance, the diamond is a crystal made up of 99.95% pure carbon atoms in an isometric, or cubic, crystal arrangement. This unique arrangement of the carbon atoms that makes diamond look and behave differently from other pure carbon minerals, such as graphite. Emerald Cut - A step cut, usually rectangular. Excellent Cut - A GIA and HRD-CGL grade for excellent cut and polish of brilliance. Extra Facet - A facet placed asymmetrically and not required by the cutting style. Eye-Clean - A description for a diamond with no blemishes or inclusions that are visible to the naked eye. Facet - A plane, polished surface of a diamond. Faceted Girdle - A girdle cut into 32 facets. Fancy Diamond - A diamond with an attractive natural body color, not including light yellow or light brown. Feather - A separation or break due to cleavage or fracture, often white in appearance. Flaw - An imperfection of a diamond. Fluorescence - The bluish glow of a diamond in high ultraviolet lighting conditions. Strong blue fluorescence may make a diamond seem oily in daylight. Fracture - A crack on the diamond's surface. GIA (Gemological Institute of America) - This organization provides credible diamond grading reports. Girdle - The diamond's outer edge or the widest part, forming a band. Hue - Pure, prismatic color. Hues include shades of red, organdy, yellow, green, blue, violet, and purple. Included Crystal - A mineral crystal contained in a diamond. Inclusion - Imperfection internal to the diamond. Internal Graining - Internal indications of irregular crystal growth. These may appear cloudy, like faint lines or streaks, or may be colored and reflective. Loupe - Magnifying glass usually of 10X. Marquise Cut - A type of fancy shape diamond, which is elongated with points at each end. Naturals - Small fragments of the original rough diamond's surface that are left on the polished diamond, usually on or near the girdle. While blemishes, they also can be a sign of expert cutting. The presence of a natural reflects the cutter's ability to design a beautiful polished gem, while keeping as much of the original crystal's weight as possible. Naturals often do not affect the clarity grade. Needle - A long, thin included crystal. Oval Cut - A type of fancy shape diamond. Pavilion - The part of the diamond below the girdle. Pear Cut - A type of fancy shape diamond that resembles a teardrop. Pinpoints - Very small spots internal to a diamond. A cluster of pinpoints can form a cloud. Pit - A little opening that appears like a white dot. Point - 100th of a carat. Polish Lines - Small parallel lines caused by polishing. Polish lines can be fine parallel ridges on a single facet caused by crystal structure irregularities, or tiny parallel polished grooves produced by irregularities in the scrape surface. Polish Mark - Clouding of the diamond's surface caused by too much heat (also called burn mark, or burned facet), or uneven polished surface resulting from structural irregularities. Princess Cut - A type of brilliant cut fancy shape that can be either square or rectangular. Radiant Cut - A type of brilliant cut fancy shape that resembles a square or rectangle with the corners cut off. Surface Graining - Surface indication of structural irregularity. Symmetry - Symmetry indicates the quality of as diamond's cut, graded as Ideal, Excellent, Very Good, Good, Fair or Poor. Table - The flat, large facet on the diamond's top. Table Percentage - 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. |
