| Abrasion |
Tiny nicks along facet junctions, producing white fuzzy lines instead of sharp crisp facet edges. |
| Baguette |
A step cut in the shape of a small rectangular stone. May be tapered at one end. |
| Bezel |
A facet on the Crown, or upper part of the Diamond above the Girdle. |
| Blemish |
Surface imperfection external to the Diamond. |
| Bruise |
An inclusion consisting of surface crumbling, often accompanied by tiny, root like feathers . |
| 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. |
| Cavity |
An inclusion consisting of a large or deep opening in the stone. |
| Certificate |
Laminated document by a gemological institute to describe a Diamond's characteristics. |
| 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 means, show no inclusions or blemishes when examined by a skilled grader under 10X magnification. If other factors are equal, flawless stones are most valuable. |
| Cloud |
A group of tiny white inclusions which result in a milky or cloudy appearance. |
| 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. |
| 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. |
| CZ |
Cubic zirconium. A widely used simulant, an imitation for a natural diamond. CZ, although easy detectable by its 80% higher weight than a diamond of the same prortions or by thermal conductivity testing, does often fool lay persons. |
| Facet |
Angled cut surface, polished surface of a diamond. |
| 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. |
| Feather |
A separation or break due to either cleavage or fracture, often white and feathery in appearance. |
| Flaw |
An imperfection of a stone. |
| Fluorescence |
Mostly blueish glow of a Diamond in high ultraviolet lighting conditions. Ratings: none, faint, slight, medium, strong blue. Strong blue fluorescence may cause the Diamond to appear oily in daylight. |
| Fracture |
A crack on the Diamond's surface. |
| GIA |
G emological I nstitute of A merica. Reliable diamond grading reports. Diamond research. |
| Girdle |
The outer edge or the widest part of the diamond forming a band around the stone. |
| 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, 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. May appear milky, like faint lines or streaks, or may be colored or reflective. |
| Irradiated diamond |
A diamond which has been exposed to radiation. |
| Laser Indentification |
Microscopical small inscription by a laser on a diamond for indentification. Can be the diamond certificate number, a message, brandname and number or otherwise. |
| Loupe |
Magnifying glass usually of 10X. |
| Melee |
Small Diamonds under .20 carat. Usually .10ct diamonds. |
| 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. |
| Natural |
Part of the rough Diamond remaining on the Diamond, having survived the cutting process. This is usually the sign of a cutter attempting to maximize the weight retention of the rough Diamond. Frequently noticed on .00ct Diamonds in order to maintain a commercial interesting weight i.e. 2.00ct . |
| Nick |
A notch near the girdle or a facet edge. |
| Off Make |
A poorly proportioned Diamond. |
| Old European Cut |
Early round cut similar to the Round Brilliant Cut, but carrying a very small table and heavy crown. Not as popular today because it does not return the same brilliance as the modern brilliant. |
| 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 |
100th of a carat. |
| Round Brilliant cut |
The most common cut usually containing 58 facets. Also the most brilliant cut, in terms of most efficient use of light to increase brilliance and fire, hence the name. |
| Scratch |
A linear indentation normally seen as a fine white line, curved or straight. |
| Surface Graining |
Surface indication of structural irregularity. May resemble faint facet junction lines, or cause a grooved or wavy surface, often cross facet junctions. |
| Treated Diamond |
Fancy color treatment: A diamond with a bodycolor induced by some form of artificial irradiation, often in conjunction with controlled heating (known as annealing). Other possible treatments of diamonds are: coating, fracture filling, spot bleaching by laser, electromagnetic conduction, whitening by extreme pressure and heat, ... |
| Zirconium, Zirconia |
Zr is a natural occurring metal. Synthesized in crystal form, cubic zirconia CZ, as simulant. |
