A comprehensive glossary with the entire lingo you need to know in order to better understand diamonds.

 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 on the surface of diamonds visible along facet junctions. Gives the diamond a fuzzy look instead of sharp facet lines.

Adamas

Greek word which means unconquerable. The term diamond is derived from this.

ADL

Renowned group that offers many services, pricelist and support on the Antwerp diamond market.

American Gem Society (AGS)

Professional jeweler's society with a renowned laboratory that grades diamonds and provides diamond grading reports.

American Standard cut

Ideal cut

Antwerp Diamond Bourse

Global market and meeting place for various diamond dealers to trade in polished diamonds.

Appraisal

Written estimate specifying the approximate retail replacement value of the diamond. The document can be used for insurance purposes and needs regular updation.

Argyle

Diamond mining region located in Western Australia

Asscher

Fancy diamond present in the shape of a square emerald cut. Originally designed by Asscher, an Amsterdam based diamond cutter in 1900.

Asterism

Star effect caused by light reflecting off inclusions inside a diamond

Aventurescence

Shiny reflection caused when tiny inclusions sparkle in light in a diamond.

Baguette

French term meaning rod or loaf of bread. Step cut of the diamond giving it a rectangular shape.

Ballerina

Form of diamond setting where a large central diamond is surrounded by a series of diamonds cut in baguette style. Setting looks like a ballerina's skirt.

Bar setting

Diamond setting, where in a circular band of diamonds, each stone is held by a long thin bar shared between two diamonds.

Bearding

Or bearded girdle refers to hair like fractures reaching inside the stone

Bezel facets

Kite shaped facets also known as top main facets present on the crown of a diamond.

Blemish

Imperfections present on surface of diamond.

Blood diamonds

Or conflict diamonds. Used to fund illegal activities of terrorist groups..

Blue white diamonds

Initially referred to diamonds without a distinctive body color. However now, as per Federal Trade Commission, refers to diamonds with distinct blue body color.

Bort

Industrial grade of diamonds

Bow tie

Effect caused in fancy shaped diamonds when light leaks out from the bottom of a diamond causing a shadowy area.

Brilliance

Reflection of white light coming from the diamond.

Brilliant cut

Round diamond with 57 facets (58 in case culet is present). The most brilliant form of diamond as compared to other cuts.

Brillianteering

The last part of polishing diamond, where the brillianteer adds twenty-four facets to the crown and sixteen facets to the pavilion.

Bruise

Surface inclusion with crumbling on the diamond's surface along with tiny feathers.

Bruting

Cutting or girdling. Process involves grinding one diamond against another to give it its basic shape.

Carat weight

Standard unit of weight of diamonds. One carat is equivalent to 1/5 of one gram. Not to be confused with Karat, which is used for stating the amount of pure gold.

Cavity

diamond flaw represented by a large hole in a diamond.

Canary diamonds

Diamonds that are golden yellow in color with fluorescence in yellow, golden and orange colors. Also known as fancy yellow.

Canary Diamond

Centenary diamond

Weighing 273.8 carats, this is the third largest diamond to be produced from the Premier mine.

Central Selling Organization (CSO)

London based trading arm of De Beers Consolidated Mines Ltd, commonly referred to as the ‘Syndicate'.

Certificate

Laminated document provided by gemological laboratories to verify the 4Cs of a diamond and its various characteristics.

Channel setting

Popular ring setting for wedding and engagement rings. Here stones are set next to each other without any metal separating them.

Chip

Small missing piece in a diamond caused due to normal wear and tear or due to diamond cutting.

CIBJO

World jewelry confederation that deals with diamonds, silver and various other stones. Known as Confederation International de la Bijouterie, Joaillerie Orfèvrerie des Diamantes.

Clarity

One of the 4Cs of diamonds to indicate the level of flawlessness in a diamond. Graded on a scale from flawless (FL) to Imperfect (I).

Clarity enhancement

Range of processes used to improve the clarity grade of diamonds.

Cleavage

A break in diamonds parallel to one of its crystallographic planes.

Cloud

A gathering of tiny inclusions in a diamond giving the stone a cloudy appearance.

Cluster setting

Diamond setting, where one large central diamond is surrounded by many small stones.

Coating

Coloring of a diamond with surface coating to hide its true body color. The coating may be extensive or limited to a couple of pavilion facets.

Colored stones

All natural gemstones, except diamonds.

Crown

Portion of the diamond above the girdle to the table.

Crown angle

Angle formed between the girdle plane and bezel facets. It helps to determine the amount of light dispersion and hence the brilliance of a diamond.

Crystals

Diamond inclusions in the form of mineral deposits or other diamonds inside the diamond.

Crystallography

The internal structure of a diamond (usually as octahedron, tetrahedron, cube or rhombic dodecahedron) that has a direct influence on its external morphology.

Culet

Smallest facet that may be present at the bottom of a full cut diamond. Is of negligible diameter or will cause light to leak out from the diamond.

Cullinan diamond

One of the largest ever diamonds (original weight of 3106 carats) to be discovered in the Premier mines of South Africa.

Cushion cut

A mixed cut in diamond giving it the shape of a square pillow.

Cut

One of the 4Cs of a diamond that determines its brilliance and overall beauty. It refers to the proportions given by a diamond cutter.

Dahlia

A form of diamond shape where the stone is oval in shape with flat ends. The stone has 51 facets, with 37 on the crown and 14 on the pavilion.

Diamond

A crystal of over 99% pure carbon, arranged in an isometric, cubic or crystal form. Has a hardness of ten, refractive index of 2.417 and 3.52 specific gravity.

Diamond Development Initiative (DDI)

An initiative taken on with the mission to address the political, social and economic aspects of diamond mining.

Dark field condition

Condition caused when a stone is tilted in an angle that makes selected facets appear black. Prevalently used to locate flaws.

Depth percentage

Ratio which refers how deep the diamond is as compared to its width. An important factor for measuring diamond brilliance and value.

Diamond gauge

Instrument used for measuring the length, width and depth of diamonds in millimeters.

Diamond radiation

Diamond enhancement method of irradiating diamonds with high energy particles like protons or electrons to displace the carbon and cause color centers.

Dispersion

Rainbow of colors obtained when white light passes through a diamond.

Doublets

Diamond imitations or simulants that are made of two or more components. Usually comprise of a synthetic stone with a thin layer of natural diamond.

 Dubai  Diamond Exchange (DDE)

Organization in Dubai that facilitates the trade of both rough and polished diamonds in Dubai.

Emerald cut

Rectangular shape of a diamond giving it cut corners. Also known as step cut.

Epigenetic inclusions

Inclusions formed in a diamond after its formation. Usually caused during mining and processing.

Eppler system

European system followed for measuring proportions of ideal diamonds, popular in Germany.

European Gemological Laboratory (EGL)

Renowned gemological laboratory that grades diamonds and gives certification regarding diamond characteristics.

Excellent cut

Grade awarded by GIA and HRD for brilliant diamonds that have an excellent polish and cut.

Extra facet

A false facet that is placed in a diamond without any actual use for it or without any regard to symmetry.

Eye clean

Diamonds that are graded with no inclusions visible through the table with the naked eye

Face up

View of the diamond when it is seen from the top.

Facet

Polished planes present on the surface of a diamond

Faceted girdle

Result obtained from polishing the girdle for increased reflection, such that a round diamond has 32 facets.

Fancy shape

Shape of a diamond other than round. Comprises of heart, marquise, pear, oval, emerald and trillion shapes.

Feather

Fracture in a diamond resembling the form of a feather

Fingerprint

Rare form of diamond inclusion found on diamond surface in the form of fingerprints.

Finish

The set of qualities attributed to a diamond after it is cut and polished by a diamond cutter. 

Fish eye diamond

Diamond with an extremely shallow pavilion less than 37% of average diameter, making the stone look lifeless.

Flat top setting

Kind of diamond ring setting with a continuous band

Flaw

A defect present in a diamond

Fluorescence

Glow with visible light caused when high energy rays pass through a substance. Visible in all rainbow colors with a domination of blue, white, green, pink and yellow in diamonds.

Four Cs

The four major characterstics of cut, color, clarity and carat weight that determine a diamond's quality

Fracture

Breakage in a diamond that is not parallel to the cleavage plane

Fracture filling

Predominant yet temporary practice of sealing fractures on a diamond

Full cut

Diamonds with a brilliant cut.

Gem quality

Stones selected during sorting process. Includes stones with excellent colors, minimal flaws, crystal shapes and good sizes.

Gemological Institute of America GIA

One of the world's leading gemological laboratory that does extensive research on diamonds, grades them and provides grading certificates

GIA proportionoscope

An optical comparator used by GIA for checking proportions of brilliant cut diamonds from .18 carats to 8 carats.

Girdle

Narrow band present around the outer circumference of a diamond. The girdle can be rough or polished and represents the junction where a setting holds the diamond.

Golden Jubilee

A yellowish brown renowned fancy diamond with the original weight of 545.67 carats discovered in the Premier mines of South Africa.

Grain lines

Crystal inclusions formed due to improper crystallization of diamond.

Heart shape cut

A fancy cut in diamonds, where the cut resembles the shape of a heart.

High pressure High temperature (HPHT)

Form of diamond enhancement technique where high pressure and high temperature are recreated (as in a diamond's natural environment of formation) in order to improve diamond color.

Hope diamond

A renowned blue color fancy diamond weighing 45 carats, known for bringing misfortune to its owners.

HRD
Hoge Raad voor Diamant. An independent and not for profit diamond institute and laboratory of Antwerp that provides impartial diamond certificates.

Ideal cut

Highest quality of cut, applicable only to round diamonds. Gives the diamond high brilliance and high prices.

Inclusion

Naturally occurring diamond imperfections in the form of pinpoints, crystals, needles etc.

Included

Clarity grades of I1, I2 and I3 awarded to diamonds with medium and large inclusions visible to the naked eye.

International Diamond Council (IDC)

Formulated by the WFDB, IDMA and CIBJO in 1979 to create universal rules for diamond trade.

International Gemological Institute (IGI)

An internationally acclaimed diamond laboratory that provides grading reports and issues appraisals for diamonds.

Iridescence

The spectrum of colors present on the surface of a gemstone or inside it.

Kimberlite

A rare form of igneous rock that may host diamonds in primary deposits. Have high contents of volatile elements.

Knife edge girdle

An extremely thin girdle that can fracture when set.

Knot

Diamond inclusion present in the form of a crystal reaching the diamond's surface.

Kohinoor

The renowned Indian diamond, rumored for its powers to make the owner a ruler of the world. Weighs 108 carats approximately and is found in the Tower of London.

Lamproite

Highly rare form of igneous rock that may host diamonds in primary deposits.

Laser drilling

Diamond enhancement process that involves drilling a hole into diamonds with the aid of laser beam to remove inclusions.

Laser identification

Process of inscribing diamonds with either a special personal message or general information (regarding the diamond brand name, number etc)

Length to width ratio

Ratio used to measure how long a diamond is as compared to its width. Specially used for analyzing the outlines of fancy shaped diamonds.

Leveridge

A micrometer specially designed for measuring the proportions of diamonds, especially expensive stones.

Loupe

Small magnifying lens used by jewelers to examine diamonds. Usually comes with standard10X magnification, to prevent different evaluations of the same flaw.

Loupe clean

Highest degree of clarity awarded by the International Diamond Council whereby the stone does not have a pinpoint flaw larger than 5 microns in diameter when seen under a magnification of 10X.

Luminescence

The phenomenon that occurs when diamonds are exposed to UV light causing them to fluoresce with visible light.

Luster

The quality and amount of light that reflects from a diamond. An important attribute while purchasing diamonds, classified as high, medium and low.

Make

The quality of finish and proportions in a diamond. A good make enhances the brilliance of a diamond.

Makeables

Diamonds that go into polishing without going through the initial preparatory stages of cleaving and sawing. Usually includes macles and cleavages among other stones.

Marquise cut

Fancy shape in diamonds comprising of elongated points at each end.

Master set

Set of diamonds (usually ones certified by GIA) used as a standard to grade color in other diamonds.

Melee

Minute diamonds of size under 0.20 carats.

Mine cut diamond

An early form of brilliant diamond cut with square girdle, large culet and high crown.

Mohs scale

The scale used for grading mineral hardness. Diamonds are graded on 10, the highest figure of the Mohs scale. Devised by Friedrich Mohs, a German minerologist.

Mounting

Trade term for the portion of jewelry on which a diamond is set.

Naats

Another diamond inclusion which represents the junction at which one diamond crystal is seen to be embedded inside a second diamond crystal.

Natural

A form of diamond blemish where some diamond rough is left on the polished surface of a diamond. Is usually done to maximize the weight of a diamond.

Needle

A diamond inclusion whereby a thin needle like crystal is present inside the diamond.

Nick

A small chip on the surface of a diamond, usually near the girdle or the facet edge.

Off make

A diamond that is poorly proportioned

Old European cut

An early version of the round brilliant cut. The cut is different from the modern round brilliant as it has a small table and large crown.

Open pit mining

Process of diamond mining that uses kimberlite pipes to extract diamonds.

Oval cut

Another fancy cut in diamonds where the cut becomes an elongated version of the round cut.

Pave

Jewelry setting where many small diamonds are mounted close together to create a diamond crust which obscures the surface of the metal on which the diamonds are mounted.

Pavilion

Portion of the diamond below the girdle

Pear cut

Another fancy cut in diamond resembling a tear drop.

Percussion mark

A dent or hole caused by external force, but leading to an internal mark. This is considered as an internal flaw.

Phosphorescence

Also known as after glow. This phenomenon is called when diamonds luminescent under UV light continue to fluoresce even when the light is turned off.

Pinpoints

Small dot shaped inclusions in diamonds. Many pinpoints together form a cloud inclusion.

Pit

Tiny opening on the diamond present as a surface blemish and looking like a white spot.

Points

One by hundredth of a carat. It is used to measure diamonds weighing less than a carat.

Polish

The finishing of a diamond's facets by a diamond cutter. Polish is graded on the scale from poor to excellent.

Polish lines

White lines that appear on a diamond due to polishing. Caused usually because of uneven surface of a diamond.

Polish mark

Marks in the form of white cloudy areas left on the diamond due to application of high degree of heat or because of an uneven diamond surface.

Princess cut

A fancy cut diamond that is either square or rectangular in shape.

Protogenetic inclusions

Inclusions that predate a diamond and are noted to be present in the vicinity of the stone while it was being created.

Radiant cut

Another fancy cut where the diamond is square or rectangular, but has the corners cut off.

Repeated twinning

Also known as polysynthetic twinning. Refers to the manner in which diamond crystallize as thin layers on top of each other.

Round brilliant

Refer to ideal cut

Saturation

The degree or presence of color in a diamond from the neutral to vivid scale.

Sawing

The process undertaken to increase the options present for preparing a stone. Can be undertaken mechanically or by using lasers.

Scaife

A horizontal wheel for polishing diamonds. The instrument is powered by an electric motor that has speeds up to 3000 revolutions per minute.

Scan DN 

Known as the Scandinavian system, a popular European system  of measuring the ideal proportions of a diamond.

Scratch

A diamond flaw caused by rubbing diamond with abrasive. Present in the form of tiny white lines.

Semi mount

A kind of jewelry setting where side stones are already mounted, but an empty set of prongs is provided usually in the center to mount a diamond.

Simulant

Imitation diamonds that are made of diamond like material, either natural or synthetic. Marketed to look like real diamonds. Examples include CZ, GGG, moissanite etc.

Single cut

Small round diamonds with approximately 16 facets instead of the regular 57 facets. The cut is employed usually in pave settings or in cases when many small diamonds are set together.

Solitaire

Term referring to a single diamond being set in a piece of jewelry.

Sparkle

The amount of light reflected from a diamond as it moves.

Spread stone

A diamond that comes with a large table and thin crown height.

Star facet

Facet found on the upper crown section of brilliant cut diamonds next to the table. One of the eight triangular facets.

Symmetry

Graded by laboratories for diamonds on the basis of how proportionate the diamond is and how the various facets are placed in accordance with each other.

Syngenetic inclusions

These are the inclusions which were noted to be formed along with the formation of the diamond. Noted to have originated from the same geological layer and have developed along with the diamond.

Synthetic diamonds

Diamonds that are not naturally formed and are created by humans.

Table

Largest facet present on the top of a diamond. The area from where maximum amount of light enters and exits a diamond.

Table percentage

Figure derived from dividing the width of the table by the average diameter.

Tang

An instrument used for manual polishing of diamonds. Comprises of three parts known as the dop, stem and legs.

Tolkowsky cut

Form of round brilliant cut which is the benchmark for ideal cuts in North America. Cut was discovered in 1919 by Marcel Tolkowsky, a renowned Belgian diamond cutter.

Tone

The position of diamond color on a grade from colorless to black.

Topaz

A popular diamond imitation, which can easily be detected through polariscopes.

Trilliant cut

A brilliant fancy triangular shape of diamond.

Twinning wisp

Cloudy area produced by distorted crystal inclusions that intertwine.

Type I diamonds

Nitrogen containing diamonds that absorb ultraviolet rays from 300nm. They also show distinct absorption bands in infrared regions of 780nm. Eg. Cape and brown series of diamonds. These are further classified as Type Ia (those containing highly concentrated nitrogen as platelets) and Type Ib (where nitrogen is evenly distributed throughout the stone).

Type II diamonds

Nitrogen free diamonds that do not show any absorption bands in infrared regions and appear more transparent in ultraviolet light up to 220nm. Further classified as Type IIa (brown to light brown stones) and Type IIb (natural blue stones).

Type III diamonds

Diamonds having a crystallographic structure that is hexagonal instead of a regular cube. Usually discovered in meteorites and synthetic diamond preparations.

Ultrasonic cleaner

A device used for cleaning diamonds and other gemstones using ultrasonic vibrations. May come with a heater.

Upper girdle facet

One facet among the fifteen present on the lower crown of the diamond.