Diamond Dictionary

a jour: An open type of mounting which leaves the pavilion facets open to the light as well as the crown; consequently light enters from the back of the stone as well as from the top.

Alluvial deposits: All deposits laid down on land by the agents of erosion, including streams, wind, and waves.

Antwerp: The most important diamond cutting center in the world and a major distribution center for polished goods.  All sizes and shapes of rough diamonds are cut in Antwerp, in contrast to many other centers where a limited range of sizes and/or shapes are fashioned.

Appraisal: A monetary evaluation of a diamond or diamond jewellery.  For insurance purposes, it is based on an estimate of a retail replacement value and should describe the piece in detail, giving color, clarity grades, all proportion characteristics, exact measurements and plots of inclusions on or in the diamond.  This provides protection in the event of loss or damage.

Baguette (bah-get): A French word meaning rod.  A style of step cutting for small, rectangular shaped diamonds.

Ballerina setting: A popular type of setting in which a central stone is surrounded by baguette diamonds mounted close together, side by side and radiating out in an undulating ballerina skirt-like effect.

Belly: The central area of a marquise, oval or pear shape diamond, when viewed from above.

Blemish: A term used to refer to a surface imperfection on a fashioned diamond, e.g. a nick, knot, scratch, abrasion, minor crack or poor polish.

Blue ground: A diamond miner's name for Kimberlite, the rock that contains diamonds in the South African pipe mines.

Blue white: A colloquial expression that refers to a diamond that is completely colorless.  About 2% of all gem diamonds are true colorless diamonds.  They are very rare and are regarded as the most desirable among fine stones.  This term is not used by experts in describing a colorless diamond because it's flagrant misuse has rendered the term meaningless.

Body color: The color of a diamond as observed when examined under diffused light against a hueless background free from surrounding reflections.

Brilliance: The total effect created by the reflection and refraction of light in a diamond.  The more light that is reflected and the less refracted out of the stone, the greater the diamond's brilliance.

Brilliant cut: The most popular of all diamond cuts, consisting of 58 facets.  Modifications of the round brilliant include such fancy shapes as the marquise, pear, oval, square, heart-shape and many others.

Brillianteering: The placing and polishing of the 40 remaining facets on a brilliant-cut diamond after the main bezel and pavilion facets have been placed and polished by the blocker.

Canary diamond: A term used for an intensely colored yellow diamond.  Such a diamond is called a "fancy".  The well-known Tiffany is canary yellow.

Cape: A broad range of diamond color grades for stone that show a distinct yellow tint when looked at face up.

Carat: A unit of weight for diamonds.  There are 100 points to a carat, like cents in a dollar.  A carat is equal to 1/5 of a gram and there are 142 carats to an ounce.  Price per carat varies and because larger diamonds are more rare, they cost more per carat.

Carbon: A chemical element occurring in nature from which diamonds are crystallized under tremendous heat and pressure.

Carbon spots: A term that is used in the jewellery trade to refer to any black-appearing inclusion or imperfection in a diamond.  Actually, black inclusions are rare, although some may occasionally be graphite or small particles of another black mineral.

Carob: The origin of the "carat weight" stems from the seed of the Carob tree.  Carob seeds were used by ancient lapidaries to balance their scales.

Chip: There is no such thing as a diamond chip, but this term is used to describe a small rose-cut or single-cut diamond.

Clarity grade: The term used to describe the presence of absence of inclusions in a diamond.  Most diamonds, when formed, contain imperfections of one kind or another.  The fewer inclusions in a finished diamond, the higher the price.  Unless the inclusions interfere with the passage of light through the diamond, they will have little effect on a diamond's beauty.  Diamonds are commonly graded as follows: flawless or perfect; very very slight inclusion; very slight inclusion; slight inclusion; and inclusion.

"Commercially perfect": A clarity classification used to imply that a diamond is "almost perfect".  It is commonly used to mislead the unwary into the belief that a slightly imperfect to imperfect stone has a much higher grade than it's actual rating.  It is prohibited by the American Gem Society for use by it's members.

Cutting: The several steps in the preparation of a fashioned diamond from the rough are called cutting.  It includes the operations of sawing, cleaving, grinding, polishing and faceting.

Diamond: A mineral composed of ordinary carbon, like graphite in a lead pencil, which was crystallized deep within the earth under tremendous heat and pressure over a hundred million years ago.  It is the hardest substance known to man.

Diamond bourse: A wholesale polished diamond exchange where trade merchants meet to transact business.  Diamond bourses are held in major diamond cutting centers of the world such as Antwerp, Johannesburg, New York, Tel aviv and Bombay.

Dispersion: The property of transparent gemstones the separate white light into the spectral colors.  Diamonds have the highest dispersion of any of the popular, natural colorless gems.

Emerald cut: A popular diamond shape, based on a form of step cutting.  An emerald cut diamond is rectangular with facets on the sides, ends and across the corners.  If it appears square it is called a square emerald cut.

Eternity ring: A diamond eternity ring of anniversary ring is a half or full circle of small diamonds set in precious metal and given by a man to his wife on the occasion of an important anniversary.

"Eye-clean": A term that implies that no internal flaws are visible to the unaided eye of the qualified gemmologist.

Facets: The tiny planes of polished surfaces placed on a diamond that trap the light and make the diamond sparkle.  A finished polished diamond has 58 facets, each placed to exact proportions to allow it to produce the greatest fire and brilliance.

Fancy cut: Any style of diamond cut other than the round brilliant or single cut.  Fancy shapes include the marquise, emerald cut, heart shape, pear shape, triangle and many more.

Fancy diamond: Any diamond with natural, definite body color other than white.  Fancies are valued for their depth of color and come in virtually all colors of the rainbow, such as: red, green, canary yellow, pink, blue and brown.

Fashioning: A general term for the operations such as cleaving, sawing, rounding up, grinding and polishing that are necessary to transform a rough diamond into a cut-and-polished gemstone.

Fire: The play of colors created by the dispersion of light in a diamond

Flawless: A jeweller's term for a diamond that has no inclusions when viewed under 10-power magnification.  There are very few flawless diamonds.

Four C's: The four factors which determine the price of any diamond: Carat weight, Clarity, Color and Cut.

Full-cut brilliant: Term used correctly for a brilliant cut diamond with the usual total of 58 facets, consisting of 38 facets and a table above the girdle and 24 facets and culet below.

Gemmologist: A specialist in gem materials who has successfully completed recognized courses of study in gem identification, pricing, grading and appraising.

Girdle: Not something one wears, but a jeweller's term to describe the outer edge or periphery of a polished stone.

Hardness: Stones are measured on a scale of 1 to 10, 10 being the hardest.  Diamond being a 10 is the hardest substance known to man.  Only a diamond can scratch or cut another diamond.

Heart-shaped diamond: A variation of the brilliant cut diamond.  It is a pear shape with a notch in the round end to form the heart cut.

Illusion setting: A method of setting a small diamond in a large polished plate fixed by claws, in order to increase it's apparent size.

Imperfection: A general term used to refer to any internal or external flaw or blemish on a fashioned diamond.  The terms flaw, characteristic and imperfection are usually used interchangeably.

Inclusion: Any visible internal marks or birthmarks such as carbon spots, feathers, bubbles or specks found in a diamond by a trained expert either with the naked eye or under 10-power magnification.  Inclusions are not defects, but rather individual characteristics of each diamond.

Color grade: The relative position of a diamond's body color on a colorless-to-yellow scale.  Nearly all diamonds have a yellowish tinge, some so faint only an expert's eye can see it.  Starting with colorless, the value of a diamond decreases as the more common yellow tinge deepens.

Jubilee cut: A rarely used variation of the brilliant cut diamond, consisting of 88 facets; named in commemoration of Queen Victoria's accession to the throne in 1897.

Karat: Not to be confused with carat weight of a diamond.  Karat refers to the proportion of pure gold in an alloy.  Pure gold is 24 Karat; 10Karat is 10/24 or 41.6% pure gold.

Kimberlite: A blue-colored rock or ore from which most diamonds are found.

Lapidary: A cutter, grinder and polisher of gem stones.

Loupe: A small magnifying glass used by a jeweller in studying a diamond's internal and external characteristics.

Make: A trade term that describes the proportions and finish of a diamond.  For example, good make refers to a diamond that is well-proportioned, symmetrical and well-polished.

Marquise cut: A variation of the brilliant cut diamond in which the diamond is boat-shaped i.e. long and pointed at both ends.

Master diamonds: Fashioned diamonds of known color grades that are used as comparison stones when grading other diamonds for body color.

Mêlée: A term used to describe a collective number of small brilliant cut diamonds.

Navette: A French term meaning "little boat" or "boat-shaped", used to describe a marquise cut.

"North Light": The traditional light source used by gemologists when grading diamonds.

Octahedron: The most common shape of a diamond in it's rough form.  It has 8 equilateral triangular faces.

Old mine cut: An early form of brilliant cut with nearly square, cushion-shaped girdle outline.

Oval cut: A brilliant style of cutting in which the diamond is an adaptation of the round but appears larger than a round cut of the same carat weight.

Parure: A French term used to describe a matching set of jewels consisting of three to seven pieces, i.e. necklass, earrings and ring.

Pavé setting: A manner of setting diamonds in which many small cut stones are places close together to create a pavement effect.  The result is a glowing all diamond surface.

Pavillion facets: Those facets on any fashioned stone located on the pavillion or base (i.e. below the girdle).

Pear-shaped cut: The English term used for the French "pendelogue" which is related to our word pendant.  This adaptation of the brilliant cut has one wide end curving smoothly to a point.  In a ring, the point of the pear is always worn towards the fingernail.

Piqué: A French word meaning pinprick.  It refers to interior marks and inclusions in a diamond.

Rivière: A style of necklass consisting of a string of individually set stones to form literally a "river of diamonds".

Rose cut: An early style of cutting that is thought to have originated in India and to have been brought to Europe by the Venetians.

Rough diamond: A diamond in its natural state.  An uncut or unpolished diamond.

Single cut: A simple form of cutting a small diamond so that it has only 16 facets.

Smalls: Any fashioned or rough diamond ranging between Mêlée and one carat in size.

Solitaire: A term used to describe a ring with one diamond.

Square cut: An equal-sided, sharp cornered form of step-cutting.

Table: The large facet that caps the crown of a facetted diamond.

Tiffany setting: A raised, prong-type setting for solitaire diamonds introduced to the trade in 1886 by Charles L. Tiffany.

Treated diamonds: A diamond that has been coated, laser drilled, irridated or otherwise treated to alter it's color or appearance.

Trillion cut: A triangular cut, with a shallower depth than the brilliant cut, designed to give the appearance of more diamond for less weight.

VS: Very slightly imperfect or included refers to a clarity grade between very, very slightly imperfect and slightly imperfect.  A diamond graded VS has light flaws visible to the trained eye only under 10-power magnification.

VVS: Very, very slightly imperfect refers to a clarity grade immediately below internally flawless.  Diamonds graded VVS have minute surface or internal blemishes visible to the trained eye under 10-power magnification.