Abrasion

Tiny nicks along facet junctions, producing white fuzzy lines instead of sharp crisp facet edges.

AGS

American Gem Society Laboratories. Founded in 1996 (by the same person who started the GIA), this is the first lab to formally grade "cut" quality. Regarded by many to be as reputable as GIA.

Antwerp

Also called Antwerpen in Flemish, Anvers in French. Diamond capital of the world, 2nd largest port of Europe on the river Scheldt, Belgium. Home town of our parent company: Antwerp Diamond House.

Baguette

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

Bearded girdle, or Bearding

Tiny, numerous, hairlike fractures extending into the stone.

Bezel

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

Blemish

Surface imperfection external to the 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 inclusion 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.

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.

CGL

Central Gem Laboratory, established in 1970 in Tokyo. Diamond grading and Identification. Grading of “Hearts and Arrows”. Overseas office in cooperation with the HRD in Antwerp since 1992.

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.

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.

Colour

Grading colour in the normal range involves deciding how closely a stone's body colour approaches colourlessness. Most diamonds have at least a trace of yellow or brown body colour. With the exception of some natural fancy colours, such as blue, pink, purple, or red, the colourless 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

Cut refers to 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.

Emerald cut

A step cut, usually rectangular.

Everly 144 cut

A brilliant cut with 144 facets, a US-patented (#3286-486) cut with spectacular brilliance, suited in particular for solitaire set jewelry

Excellent Cut

A brilliant cut, with excellent proportions according to CGL, AGL, GIA or AGS ratings. ie. generally: crown angle 32.5 - 35.5 degrees, pavilion depth: 42.0 - 44.5%, total depth: 59 - 62.4%, table 52 - 58%

Extra Facet

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

Facet

Plane, polished surface of a diamond.

Faceted Girdle

Sometimes cutters polish the girdle into 32 facets.</TD< tr>

Fancy Diamond

A diamond with an attractive natural body color other than light yellow or light brown. Fancy also refers to a shape that is other than a round brilliant (.g. pear, princess, emerald cut, cushion, asscher, oval, heart, marquise, radiant...etc.)

FAQ

Frequently Asked Question.

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. For more information see http://www.gia.edu/pdfs/W97_fluoresce.pdf which is the results of GIA research on this subject.

Fracture

A crack on the Diamond's surface.

GGG

Gadolinium Gallium Garnet, a modern imitation of a natural diamond; simulant.

GIA

Gemological Institute of America. Reliable diamond certification. Diamond research.

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.

Hearts and Arrows

A general term when referring to diamonds with a percise and complete pattern of hearts and arrows achieved by perfect cutting proportions.

HRD

Hoge Raad voor Diamant. An independent non profit institute in Antwerp for the Diamond industry. Reliable impartial Diamond certification controlled by Belgian state authorities.

Hue

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

IGI

International Gemmological Institute. An independent diamond grading laboratory with worldwide presence and ISO 9001 quality standard. Reliable impartial Diamond certification.

Imitation

See simulants

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 coloured 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 Hole

A tiny tube made by a laser. The surface opening may resemble a pit, while the tube usually looks needle like. May be noticeable on treated Diamonds.

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.

Moisannite

A rare crystal in nature. Synthetically created moissanite produced by Charles & Colvard is a simulant ranking a high 9.25 on the Mohs hardness scale (Diamond = 10). Its double refraction is one of the few differences with a Diamond, thermal conductivity is almost equal.

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 commercially interesting weight e.g. 2.00 carat.

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.

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.

Polish Lines

Tiny parallel lines left by polishing. Fine parallel ridges confined to a single facet, caused by crystal structure irregularities, or tiny parallel polished grooves produced by irregularities in the scape surface.

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 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.

Saturation

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

Scratch

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

Simulant

Also called: Imitation. Any diamond like material, either natural or artificial, which is marketed as look-alike for a natural diamond. i.e. Glass, zirconium, YAG, GGG, moissanite…etc.

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.

Tone

A colour's position on a colourless-to-black scale.

Treated Diamond:

Fancy colour treatment: A diamond with a body colour 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, …etc.

Twinning Wisp

A cloudy area produced by crystal structure distortion, usually associated with twinning planes.

YAG

Yttrium Aluminum Garnet, a modern simulant, so an imitation for a natural diamond

Zirconium, Zirconia

Zr is a natural occurring metal. Synthesized in crystal form, cubic zirconium as stimulant.