Glossary & Picture Library, learn

The Spark of Confidence

Glossary

Abraded Culet

The sharp point at the bottom of the diamond can become damaged and worn away with wear. An abraded culet can look “fuzzy” under magnification, and affect the polish grade of a diamond.

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Abraded Facet Edge

The sharp edges where diamond facets meet can become damaged and worn away with wear.  An abraded facet edge can look “fuzzy” under magnification, and affect the polish grade of a diamond.

Abraded Facet Edge

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Abrasion

Type of blemish that looks like a bruise or scratch on the surface of a diamond. Abrasions can affect the polish grade of a diamond.

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Adamas

Archaic Greek word from which the word ‘diamond’ is derived. Adamas means ‘indestructible’.

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Annealing

Treatment to artificially enhance the colour of a diamond with a slow-heating process. Irradiated diamonds are usually annealed to further modify or enhance their colour.

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Appraisal

Written estimate of the approximate retail replacement value of a diamond or piece of diamond jewellery. An appraisal is not a diamond certificate or diamond grading report.

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Asscher Cut

Diamond cut or shaped into a square with the corners cut off, with rows or steps of elongated facets running parallel to the girdle on both the crown and the pavilion. It is similar to an emerald cut, but squared instead of rectangular, and has a pointed culet.

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Baguette Cut

Diamond cut or shaped into a rectangle with sharp corners, and rows or steps of elongated facets running parallel to the girdle on both the crown and the pavilion.

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Bearding

Bearding refers to tiny, hairline cracks along the girdle of a diamond that look like whiskers penetrating into it; the girdle can then appear to have a “fuzzy” outline. Bearding can affect both the clarity grade and the polish grade of a diamond.

  

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Bezel Facets

Kite-shaped facets on the crown of brilliant cut diamonds. Also known as “top-main” facets.

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Black Diamond

A very dark, opaque diamond which appears black. Black diamonds are heavily included with graphite, blocking all or almost all transmission of light.

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Blemish

A blemish is a flaw on the exterior of a diamond, such as a scratch, abrasion, nick or chip. Blemishes are plotted (drawn) in “green” on the plotting diagram of a diamond certificate. Blemishes affect the polish grade of a diamond.

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Blood Diamond

Diamonds that originate from areas controlled by rebel forces that are opposed to the governments in power, and are used to finance wars against these governments along with other resources like oil and timber. The Kimberley Process has been put in place to combat trade in blood diamonds, also known as 'conflict diamonds'. Click here to learn more about conflict diamonds and the Kimberley Process.

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Blue Diamond

A coloured diamond with a natural blue body colour. Blue must be the predominant colour, but it may be modified by shades of grey, purple, or green. The colour in natural blue diamonds is created by the carbon-boron when the diamond is forming. Natural blue diamonds are extremely rare; some blue coloured diamonds with sufficient saturation fall into the valuable fancy blue colour category of diamonds.

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Blue-white

An informal and often misused trade expression that refers to a completely colourless diamond. The diamonds were usually lower cape series diamonds with strong blue fluorescence.

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Bow Tie

The bow tie effect is a dark shadow across the center of a fancy shape diamond, in the shape of a man’s bow tie. This may be a sign of a poorly cut diamond - it is normally seen in diamonds that are cut too flat, too deep, or with badly arranged pavilion facets.

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Briefca

A small folded envelope-like paper used to safely hold a diamond. Information about the diamond is generally written or printed on the outside of the briefca.

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Brilliance

The amount and intensity of light reflected to the eye through the surface of a diamond. Brilliance is a very important factor in creating beauty and life in a diamond. The proportions of the diamond are most important for light return, but all aspects of the four c’s contribute to creating brilliance.

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Brilliant Cut

A style of diamond cut, using triangular or kite shaped facets that radiate out from the center of the diamond to the girdle. The standard round brilliant cut consists of 32 facets plus a table above the girdle and 24 facets plus a culet below the girdle. Other shapes besides round can be faceted as brilliant cuts, including marquise cut, oval cut, pear cut, heart cut, and radiant cut diamonds.

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Briolette Diamond

Diamond cut or shaped into a full tear-drop with a circular cross section; briolettes are generally covered with triangular facets.

Necklace with a dangling Briolette Pendent

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Bruted Girdle

An unpolished diamond girdle, with a rough or frost-like appearance. The girdle may be either bruted, faceted, or polished.

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Burn Mark

A blemish on the surface of a diamond that looks like an oily or frosted area. When a diamond is polished too quickly, heat from excessive friction builds up and leaves a mark on the surface. Burn marks affect the polish grade of a diamond.

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Calf’s Head Diamond

Diamond cut or shaped to look like a triangle with all three corners cut off, similar in outline to the head of a calf.

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Canary Diamond

Term used to describe an intensely or vividly bright-yellow fancy colour diamond.

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Cape Series Diamonds

A broad scale of diamond colour grades that ranges from a near colourless, almost undetectable pale yellow to increasingly tinted yellow. Once it has enough yellow saturation to qualify as a fancy colour, it is no longer called a Cape Series diamond.

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Carat

The standard unit of measuring the weight of a diamond. The origin of the word traces back to ancient times when diamonds were weighed on balances against carob beans, which held a consistent weight. One carob bean, or carat, weighs 1/5 of a gram.

Carob Bean

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Carbon

Diamonds are made of pure carbon that has been subjected to and crystallised under enormous heat and pressure. Without the pressure, graphite is formed instead of diamond. Other forms of carbon can be found in substances like coal, but these are impure forms of carbon.

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Carbon Spots

Small black graphite inclusions in a diamond. Diamonds are made of pure carbon that has been subjected to and crystallised under enormous heat and pressure. At times, not all of the carbon crystalises, and small black spots may remain.

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Cavity

Type of diamond inclusion that appears as an opening or large indentation on the surface of a diamond. A tiny version of a cavity is a called a pit. Cavities affect both the clarity grade and the polish grade of a diamond.

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Certificate

A complete, accurate report describing the specific characteristics of a diamond, issued by a recognised and independent diamond grading laboratory.  A diamond certificate lists all the characteristics of a diamond that allows you to determine its current appraisal and fair market value. Also called a Diamond Grading Report. A diamond certificate is not an appraisal and does not contain a monetary value. Click here for a guide to the information that a diamond certificate must have.

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Chameleon-Type Diamond

A very rare type of diamond that changes colour when exposed to different light and heat conditions.

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Champagne Diamond

Refers to a coloured diamond that is light-brown or light brownish-yellow in colour.

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Chip

Type of inclusion that appears as a slight break out of the edge of a diamond, larger than a nick. Chips are caused when a diamond receives a sharp knock or blow; they affect both the polish and clarity grade of a diamond.

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CIBJO

The World Jewellery Confederation, an international confederation of national jewellery trade organizations. CIBJO's purpose is to encourage harmonisation, promote international cooperation in the jewellery industry, and to consider issues that concern the trade worldwide. Foremost among these is to protect consumer confidence in the industry.

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Clarity

Term used to describe the relative presence or absence of inclusions in a diamond. Most diamonds, when formed, contain imperfections of one kind or another. Clarity, sometimes called purity, is one of the four c’s of diamond grading that determines the overall diamond quality and value.

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Clarity Enhancement

Any artificial treatment or process meant to improve the appearance of a diamond’s clarity. Laser drilling and fracture filling are examples of diamond clarity enhancement. Click here to learn more about diamond clarity enhancements.

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Cleavage

Type of inclusion that appears as a fairly smooth split or crack in a diamond, found along a plane of weakness. Cleavage is due to the directional hardness of diamonds.

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Closed Table

Trade term for a diamond that has a relatively small table in relation to the size of the diamond. A small table reduces the amount of brilliance, but may increase the amount of fire.

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Cloud

Cluster of pinpoint inclusions creating a hazy or milky area in a diamond. A diamond cloud can range from extremely sparse and faint, to dense and heavy. Clouds may also be small and localised, or spread throughout an entire diamond and affect the transparency.

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Coated Diamond or Coating

Deceptive practice where a diamond is partially or wholly ‘painted’ with a colouring agent, either to hide unattractive colour, or to enhance desirable colour. To learn more about coated diamonds and diamond treatments, click here.

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Cognac

Refers to a coloured diamond that is dark brown in colour.

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Cold Laser Inscription

The use of a very fine, precise laser beam to write a grading report number or customised personal message on the girdle of a diamond, generally for identification purposes. Cold laser inscription is 100% safe for diamonds, compared to hot laser inscription. The laser inscription is invisible to the naked eye and can only be seen with a magnifying loupe. Click here to learn more about diamond laser inscription.

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Colour

Term used to describe the relative presence or absence of body colour in a diamond. Diamonds are either cape series diamonds or coloured diamonds.

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Coloured Diamond

Any diamond with a noticeable body colour other than white. Colour in diamonds is caused by either various impurities trapped in the diamond crystal as it was forming in the earth, or by irregularities in the crystal structure itself. Some coloured diamonds fall into the valuable fancy colour category of diamonds.

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Conflict Diamonds

Diamonds that originate from areas controlled by rebel forces that are opposed to the governments in power, and are used to finance wars against these governments. Along with the other resources like oil and timber The Kimberley Process has been put in place to combat trade these diamonds, also known as'blood diamonds'. Click here to learn more about conflict diamonds and the Kimberley Process.

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Crown

Upper part, or ‘top half’ of the diamond, above the girdle.

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Crown Angle

Angle measured between the girdle plane and the bezel facets. Crown angle together with table size determine how much fire (dispersion) and brilliance a diamond shows.

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Crown Height

Distance in millimeters from the table to the girdle.

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Crown Height Percentage

Crown Height expressed as a percentage of the diameter.

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Crystal

Type of inclusion where a mineral deposit, or sometimes another diamond, is trapped inside the diamond. Crystals often look like bubbles of various shapes and sizes.

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Cubic Zirconia

Colourless, transparent, man-made material that is often used to imitate diamond - a diamond simulant.  The chemical name is zirconinum dioxide (ZrO2).

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Culet

Tiny point on the bottom of a brilliant cut diamond, or the bottom edge of a step cut diamond.  A culet can be prone to damage, thus diamonds are usually set in jewellery in such a way that the culet is protected.

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Cushion Cut

Diamond cut or shaped into a squarish or rectangular outline, with rounded corners.  A brilliant cut cushion is one of the diamond shapes that can display hearts & arrows.

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Cut

Can refer to any or all of the following: proportions, polish, symmetry, and/or shape and style of cutting (brilliant cut or step cut). The overall cut grade is one of the four c’s of diamond grading that determines the overall diamond quality and value.

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Cut Grade

Qualitative description of the overall make of the diamond, taking into consideration the proportions, polish, and symmetry. Cut is one of the four c’s of diamond grading that determines the overall diamond quality and value.

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Cut-for-Weight

A diamond that is fashioned so as to minimise the amount of rough diamond crystal cut away. Carat weight may be gained, but brilliance, fire, and beauty are lost. The resulting proportions can make some diamonds look ‘bulgy,’ 'lumpy', ‘deep,’ or ‘undersize,’ while others may be flat or have symmetry deviations.

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Depth

Distance in millimeters or percentage from the table plane to the culet. Also known as ‘total depth’ or ‘total height’.

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Depth Percentage

Total depth expressed as a percentage of the diameter.

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Diameter

Diameter is a reference measurement against which most of the proportions on a diamond are calculated. On a round brilliant cut diamond, this is the length in milimeters of a straight line going through the center of a diamond. Click here to learn which standard diameter measurements correspond to specific well-proportioned carat weights. On a fancy shaped diamond, this is the average measurement in milimeters of the length and width.

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Diamond

Mineral composed almost exclusively of crystallised carbon. Carbon, when subjected to extremely high temperature and pressure, changes form and crystallises into diamond. Only approximately 20% of natural mined diamonds are of gem quality; the remaining 80% are industrial grade diamonds.

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Diamond Bourse

Organisation of diamond industry members. The main purpose of a diamond bourse is to provide an environment for the trading of diamonds within a set of ethical business practices. All diamond bourses have a legal, ethical framework to enact regulations for members and protect consumer confidence. Also referred to as a ‘Diamond Club’.

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Diamond Dealers Club of South Africa

Diamond bourse, or organisation of diamond industry members. The main purpose of the DDCSA is to provide an environment for the trading of diamonds within a set of trading practices. The DDCSA has a legal, ethical framework to enact regulations for members and protect consumer confidence.

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Diamond Dust

Minute particles of diamond, usually used as a high-quality abrasive for diamond polishing or industrial grinding, sawing, and filing.

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Diamond Gauge

Tool used to manually measure the dimensions of a diamond.

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Directional Hardness

The bonds between carbon atoms that make up a diamond are stronger in some planes than others; this means that diamonds are marginally harder at some angles than at others. Diamonds thus have certain planes of weakness along which they can fracture, split or break. Directional hardness is related to the toughness and durability of diamonds.

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Dispersion

Visible play of colours created by the break-up of light in a diamond. When light enters a diamond, it refracts then reflects off of the pavilion facets and separates into a rainbow of colours as it shines out of the crown facets. Also known as fire.

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Durability

Overall resistance to wear and damage, considering both hardness and toughness. Diamonds are the hardest gemstone on earth, but are not the toughest - they have directional hardness.

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Eight Cut

Diamond cut or shaped in an old-style cut with only sixteen facets plus the table - eight on the crown and eight on the pavilion. This simple diamond cut is still used at times today for extremely small diamonds. Also known as a 'single-cut' diamond.

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Emerald Cut

Diamond cut or shaped into a rectangle with the corners cut off, and rows or steps of elongated facets running parallel to the girdle on both the crown and the pavilion.

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Equivalent Colour Grade (ECG)

Occasionally ‘colourless’, or cape series diamonds will have a tint of brown or grey that is not visible face-up. These diamonds are graded on the same scale of color saturation as cape series diamonds, but are graded ‘ECG’ for hue. Diamonds with ECG grading are of lower value than those with no hue. Click here to see where to find hue on a diamond Certificate.

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Extra Facet

Facets added or remaining on a polished diamond in excess of the number usually found on a particular cutting style. Extra facets are added to remove surface imperfections, and inclusions located near the surface, without losing sizeable carat weight. Extra facets affect the polish grade of a diamond.

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Eye-Clean

Refers to the clarity of a diamond that has no inclusions visible to the naked eye - magnification is needed to see any inclusions that may be present.

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Eye-Visible

Refers to clarity of a diamond with inclusions that are visible to the naked eye, without magnification.

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Faceted Girdle

Describes the girdle of a diamond that has been polished with a series of tiny steps or facets  around the circumference or perimeter.

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Facets

Any one of the flat, polished surfaces on a diamond.

1 Table

2 Bezel facets

3 Star Facets

4 Upper-Girdle Facet

5 Lower-Girdle Facets

6 Pavilion Main Facets

Table, bezel, star, upper girdle, lower girdle and pavilion facets

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Fancy Colour

Any positive diamond colour other than white, brown, or grey with a significant level of saturation. Natural fancy colour in diamonds is rare and valuable; the colour is caused by either impurities or structural abnormalities. Three factors to consider when grading a coloured diamond are body colour, tone, and saturation. Examples of fancy colours, or 'fancies': yellow diamonds, orange diamonds, pink diamonds, red diamonds, blue diamonds, purple diamonds, and green diamonds. Examples of non-fancy colours are grey and brown.

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Fancy Shape

Diamond cut into any shape other than a round brilliant cut. Some examples of fancy shape diamonds are: princess cut, emerald cut, oval cut, marquise cut, heart cut, pear cut, and asscher cut diamonds.

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Feathers

Type of cleavage inclusion in a diamond with a wispy, feather-like appearance; the feather-like part extends from the origin of the break. Feathers occur along a cleavage plane, or plane of weakness, in a diamond due to directional hardness; they may appear transparent if viewed head on, or bright white if viewed at a 90° angle.

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Finish

Qualitative description of the make of a diamond in terms of polish and symmetry.

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Fire

Visible play of colours created by the break-up of light in a diamond. When light enters a diamond, it reflects off of the pavilion facets and refracts, or bends, into a rainbow of colours as it leaves the crown facets. Also known as dispersion.

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Fish Eye

Unattractive donut-shaped white ring seen under the table of a round brilliant cut diamond with too shallow a pavilion depth. The ring is caused by the reflection of the diamond’s girdle. Diamonds with a fisheye lack brilliance, and show little life.

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Flash Effect

Bright, vivid streak of colour found in the glass-like resin filling of diamonds treated by fracture filling.

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Flat Diamond

Trade term used to describe a diamond with a very shallow crown height and/ or pavilion depth. Flat round brilliant cut diamonds with a shallow pavilion tend to show a fish eye. Flat diamonds lack some brilliance and life.

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Flawless

Refers to the clarity of a diamond with no inclusions or blemishes. Flawless diamonds are exceptionally rare.

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Fluorescence

Natural characteristic which causes many diamonds to glow under ultra violet light (UV), which is abundant in natural daylight and some artificial lighting. Fluorescence is caused by sub-microscopic structures within the diamond. Diamonds can have various colours of fluorescence, with blue being the most common.

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Four C’s

Four fundamental criteria on which the quality and value of a diamond are judged: cut, colour, clarity, and carat weight. Two additional factors, transparency and the confidence in a diamond grading certificate are also important value factors. Click here to learn more about the C’s of diamond grading.

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Fracture

Type of break or crack inclusion in a diamond that is irregular, jagged and splintery. A fracture may not follow along a cleavage plane as does a feather, but spreads across the diamond in any other direction.

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Fracture Filling

Treatment to enhance the apparent clarity of a diamond, whereby a glass-like resin is injected into feathers or fractures that reach the surface of the diamond. Feathers are visible when light reflects off of them; by filling them with a resin, light is able to travel through the feather, making it less visible. The resin causes what is known as a flash effect in the treated diamond. Fracture filling is not a stable diamond treatment and is easily altered with heat; click here to learn more.

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Gem Quality

Diamonds of a beauty and calibre suitable to be used in jewellery. Only approximately 20% of mined diamonds are of gem quality  - 80% are in fact industrial grade diamonds.

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Gemmology

The science, art, and profession of identifying and evaluating of all gemstones, including diamonds.

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Girdle

The outermost edge or rim of a diamond that outlines its shape. It is the circumference or perimeter that appears to divide the crown from the pavilion. A girdle may be faceted, polished, or bruted. The purpose of the girdle is to protect the diamond from damage such as chips.

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Girdle Thickness

The height of the girdle, expressed both in millimetres and as a percentage of the total depth.

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Grading Report

A complete, accurate report describing the specific characteristics of a diamond, issued by a recognised and independent diamond grading laboratory. A diamond grading report lists all the characteristics of a diamond that allows you to determine its current appraisal and fair market value. Also called a Diamond Certificate. A diamond grading report is not an appraisal and does not contain a monetary value. Click here for a guide to the information that a diamond grading report must have.

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Grainer

Term used to describe a diamond weighing approximately 0.25 of a carat. In ancient times, 1.00 carat was equal to about four grains of rice. A “four grainer” would thus be referring to a diamond weighing approximately 1.00 carat (4 x 0.25=1.00).

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Graining

Faint wavy, hazy, oily, or distorted transparent and sometimes shadowlike lines, either inside the diamond or on the surface of a diamond. Graining is caused by irregular growth and crystallization that takes place when the diamond is formed. Also known as “growth lines.”

  

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Green Diamond

A diamond with a natural green body colour. Green must be the predominant colour, but it may be modified by shades of yellow or blue. The colour in natural green diamonds is created by exposure to natural irradiation in the earth that produces structural defects; natural green diamonds are extremely rare. Some green coloured diamonds with sufficient saturation fall into the valuable fancy green colour category of diamonds.

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Hardness

Measure of resistance to scratching and abrasion. Diamond is the hardest material on earth, a 10 on Moh’s Scale; however, it is not the toughest. Hardness and toughness together determine the durability of diamond.

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Head

Refers to the wider, rounded end of a pear cut diamond.

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Heart Cut

Diamond cut or shaped into a heart, with a cleft in the wide end, and a softly tapered point at the narrow end.

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Hearts & Arrows

Describes a pattern that appears in some round brilliant cut and square cushion cut diamonds that have a certain parallelism and symmetry. When viewed from above through the crown, the pattern is a series of eight arrowheads. From below through the pavilion, the pattern appears as eight heart shapes. Hearts & arrows does not mean that a diamond is ideal cut, only that it is symmetrical.

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Hot Laser Inscription

The use of a laser beam to write a number or customised personal message on the girdle of a diamond, generally for identification purposes. Hot laser machines operate at a higher wavelength, and unlike cold laser inscription can penetrate into and thus damage the diamond; penetration can result in chips and fractures. Click here to learn more about diamond laser inscription.

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HPHT (High Pressure High Temperature) Treatment

Treatment to change or artificially enhance the colour of a diamond. Certain types of diamonds are subjected to extreme heat and pressure conditions in a laboratory, which rearranges their atomic structure and thus alters their colour. Click here to learn more about HPHT treated diamonds.

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Hue

Occasionally ‘colourless’, or Cape Series diamonds will have a visible negative tint of brown or grey. These diamonds are graded on the same scale of color saturation as Cape Series diamonds, but will state the hue on the certificate. Diamonds with brown, grey, or ECG hue are of lower value than those with no hue. Click here to see where to find hue on a Diamond Certificate.

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Ideal Cut

Term often used for a round brilliant cut diamond that is believed to be excellent across the board for proportions and overall make.  There are many different 'ideal cuts', the most famous being the Tolkowsky Ideal Cut. The range for ideal cut diamond parameters can often be very broad, so care must be excercised in labeling a diamond as 'ideal cut'.

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Inclusions

Internal imperfections of a diamond affecting the clarity grade. Diamonds grow deep in the earth under extreme pressure and temperature; under these conditions, it is rare to find a diamond that is internally flawless.

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Indented Natural

The original skin of the rough diamond that remains after polishing and is indented into the body of a diamond, not confined to its surface. An indented natural can affect both the polish grade and the clarity grade of a diamond.

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Independent Laboratory

Diamond grading laboratory that has no financial interest in the actual trade (buying and selling) of diamonds.

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Industrial Grade Diamond

Diamond usually not polished as a gemstone, as it does not meet the minimum quality criteria for grading. Industrial diamonds are very heavily included, lacking the transparencybrilliance and life that a gem quality diamond must exhibit. Industrial diamonds are somtimes used in their rough diamond form in jewellery.  Industrial diamonds are very useful for tools, drills, lasers, abrasives, and other such uses. Only approximately 20% of mined diamonds are of gem quality.

Industrial Grade Diamond, Very Poor Quality

  

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Internal Laser Drilling

Treatment to enhance the apparent clarity of a diamond by reducing the visibility of dark inclusions.  A precise laser beam is focused on a small dark inclusion - the black in the inclusion dissipates from the laser beam itself.  Click here to learn more about laser drilling and clarity enhancement.

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International Diamond Council

International organisation founded by the World Federation of Diamond Bourses (WFDB)and the International Diamond Manufacturers Association (IDMA) to establish standard rules for diamond grading and nomenclature.

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International Diamond Manufacturers Association

International diamond trade association committed to fostering and promoting the highest ideals of honesty and best practice principles throughout the diamond industry worldwide.

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Internationally Recognised Standards

Diamond grading rules and processes that are regulated and recognised by internationally accredited bodies. Examples of these bodies are CIBJO, LMHC, World Federation of Diamond Bourses, and the International Diamond Council.

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Irradiated Diamonds

Treatment to change or artificially enhance the colour of a diamond. Irradiated diamonds are bombarded with a variety of high-energy particles that physically alter their atomic structure, thus changing their colour. Most irradiated diamonds are annealed to further modify their colour. Click here to learn more about irradiated diamonds.

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Jewellers Association of Australia

Association of jewellers that represents and promotes the interests of retailers, manufacturers, wholesalers, suppliers, importers, exporters, watchmakers and valuers involved in the jewellery and gemstone industry in Australia.

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Kimberley Process

International certification program designed to follow a diamond from it’s origin as a rough diamond straight through to the finished product; its purpose is to ensure that diamonds come from sources which are free of conflict, unlike blood diamond, and are not traded to fund wars and violence. Click here to learn more about the Kimberley Process.

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Kimberlite

Blue-coloured rock from which most diamonds are mined, usually found in a kimberlite pipe or fissure.

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Knot

Type of inclusion; a knot is an included crystal that reaches and breaks through the surface of a diamond, sometime leaving a slightly raised or burnt area.

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Laser Drilling

Treatment to enhance the apparent clarity of a diamond by reducing the visibility of dark inclusions. A precise laser beam drills a small tunnel from the surface of the diamond to the dark inclusion; the black in the inclusion either dissipates from the laser beam itself, or else it is bleached out with acid. Click here to learn more about laser drilling and clarity enhancement.

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Life

Liveliness and beauty seen in a particular diamond, taking into consideration the amount and quality of brilliance, dispersion, and scintillation.

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Loose Diamond

Diamond that is not mounted in jewellery. Diamond certification is not possible when the diamond is set in jewellery, as none of the four c’s can be accurately assessed - only estimates are achievable.

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Loupe

Hand held magnifying lens. Diamond clarity must be graded with a 10x loupe that is corrected for spherical and chromatic aberration.

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Lower-Girdle Facets

Triangle shaped facets adjacent to the girdle on the pavilion.

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Make

Qualitative description of the overall cut quality of the diamond, taking into consideration the proportions and finish.

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Marquise Cut

Diamond cut or shaped into an oval with pointed ends. Also called a ‘navette,’ which is the French word for “little boat,” as the shape is similar to that of a boat’s hull.

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Master Set

Set of certified and registered diamonds, with known colours against which other diamonds are compared to establish their colour. A diamond master set is neccesary  for accurate colour grading. A first generation diamond master set is available to any diamond merchant or jeweller.

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Melee

Term for small polished diamonds weighing less than 15 points, or 0.15 of a carateach.

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Milky Diamond

Cloudy or hazy diamond with reduced transparency, brilliance, and overall life. A milky diamond can result from numerous factors, for example a dense cloud or extremely strong fluorescence. Click here to learn more about transparency.

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Moh’s Scale

Scale from for classifying the relative hardness used for gemstones, based on the ability of harder gemstones to scratch softer ones. Moh's scale ranges from 1 to 10, with 10 being the hardest. Diamonds are the only material on earth to rate as a 10.

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Moissanite

Near-colourless, slightly oily looking man-made material that is often used to imitate diamond - a diamond simulant.

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Nailhead

Unattractive black shadow under the center of a round brilliant cut diamond that has too deep of a pavilion. The shadow is caused by the reflection of the table. Diamonds with a nailhead look dark, lacking brilliance and life.

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National Diamond Colour Master Set

Set of certified and registered diamonds, with known colours from which other master sets may be derived. 

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Natural

Part of the original “skin” of a rough diamond that has been left on the polished diamond. Naturals affect the polish grade of a diamond, but do not have a significant impact if confined to the girdle area where they are usually located.

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Natural Diamond

Diamond mined from the earth, unlike a synthetic diamond, formed completely by nature without any human intervention or treatments.

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Needle

Type of diamond crystal inclusion where a mineral deposit, or sometimes another diamond, is trapped inside the diamond. Needles look like elongated bubbles of various shapes and sizes.

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Nick

Type of diamond blemish that that appears as a tiny break out of the edge of a diamond, not large enough to be a called a chip and usually confined to the girdle. Nicks affect the polish grade of a diamond.

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Octahedron

One of the most coveted crystal shapes for a rough diamond, with eight triangular faces that look as though two four-sided pyramids have joined together at the base.

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Off-Make

Trade term for a diamond that has been badly polished or finished. It has flaws in the overall make.

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Old Mine Cut

Diamond cut or shaped in an old-style cushion cut manner, with a deep pavilion depth, closed table, high crown height, and large facet on the culet.

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Oval Cut

Diamond cut or shaped into an ellipse and covered with triangular facets in a brilliant cut style.

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Overblue

Refers to a diamond that glows (fluoresces) strong blue under long wave ultraviolet light; in the past the term was used misleadingly to imply a diamond with superior colour. In fact, some diamonds with a high colour grade that have very strong fluorescence can look oily or milky under daylight.

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Pavilion

Lower part, or ‘bottom half’, of a diamond below the girdle.

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Pavilion Angle

Angle measured between the girdle plane and the pavilion main facets.

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Pavilion Depth

Distance in millimeters or percentage from the girdle to the culet.

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Pavilion Depth Percentage

Pavilion depth expressed as a percentage of the diameter. Pavilion depth is an extremely important proportion to the brilliance of a diamond; diamonds with a pavilion that is too deep will have a nailhead, while diamonds with a pavilion that is too shallow or flat will have a fish eye.

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Pavilion Main Facets

Kite-shaped facets clustered from the culet and extending to the girdle.

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Pear Cut

Diamond cut or shaped into the outline of a tear-drop or a pear, with a rounded head tapering to a point.

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Phosphorescence

Phenomenon that causes some diamonds to continue “glowing in the dark,” after a light source is removed. Phosphorescence is much more common in synthetic diamonds than in natural diamonds.

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Pink Diamond

A coloured diamond with a natural pink body colour. Pink must be the predominant colour, but it may be modified by shades of purple, orange, and yellow. The colour in natural pink diamonds is created by irregular crystal structure. Some pink coloured diamonds with sufficient saturation fall into the valuable fancy pink colour category of diamonds.

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Pinpoints

Very tiny diamond crystal inclusions that are too small in size to distinguish their individual shapes. One pinpoint looks like a small “dot” under 10x magnification. Clusters of pinpoints create a cloud.

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Pit

Type of diamond blemish that appears as a tiny opening or indentation on the surface of a diamond. Large pits are called cavities. Pits affect the polish grade of a diamond.

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Pitted Facet

Diamond facet with numerous pits. Pitted facets affect the polish grade of a diamond.

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Plotting Diagram or “Plot”

Diagram of the approximate relative size, location, and type of internal inclusions and external blemishes of a diamond. A plotting diagram is often used for identifying a particular diamond.

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Point

Term for one hundredth of a carat. For example, a fifteen-point diamond weighs 0.15 carats. It could also be called a fifteen “pointer”.

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Polish Grade

Qualitative analysis of the overall surface condition of a diamond. The quality of polish is determined by the care put in by a polisher when finishing a diamond, and is important to the brilliance and scintillation given off by a diamond.

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Polish Lines

Lines left on the surface of the diamond which are visible under magnification, normally removed during the final diamond polishing process. Polish lines can affect the polish grade of the diamond.

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Polished Girdle

Describes the girdle of a diamond that has been fully polished smooth and clear around the entire perimeter. Step cut diamonds such as emerald cut and baguette cut diamonds usually have a polished girdle, and some brilliant cut diamonds may have polished girdles as well.

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Princess Cut

Diamond cut or shaped into a square or rectangle. Princess cuts combine features of both step cut and brilliant cut diamonds.

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Proportion Grade

Qualitative analysis of the overall proportions on a round brilliant cut diamond. Fancy shaped diamonds are not proportion graded; unlike round cut diamonds, there is no defined range of proportion standards for fancy shapes.

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Proportions

Relations between the dimensions and angles of a finished diamond. Examples of specific proportions are table size, depth percentage, and crown angle. Proportions are extremely important to the beauty, brilliance, and life in a diamond. Click here to learn more about proportions on a diamond grading report.

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Radiant Cut

Diamond cut or shaped into a square or rectangular princess cut, with the corners cut off.

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Red Diamond

A coloured diamond with a natural red body colour. Red must be the predominant colour, but it may be modified by shades of pink or purple. The colour in natural red diamonds is created by irregular crystal structure. Natural red diamonds are the most rare of all diamonds. Some red coloured diamonds with sufficient saturation fall into the valuable fancy red colour category of diamonds.

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Rough Diamond

Diamond in its natural state, exactly as it is found in the earth, prior to undergoing cutting, polishing, or alteration of any kind.

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Round Brilliant Cut

Diamond cut or shaped into a circular outline or circumference, with a cone-shaped pavilion. The standard round brilliant diamond has 57 or 58 facets, and is the most popular style of cutting.

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Saturation

Intensity and purity of colour in a diamond. Both cape series diamonds and fancy shape diamonds are graded on a scale of increasing saturation, in addition to hue and tone.

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Scintillation

Sparkle of a diamond as light reflects off of its surface when it is moving, seen as quickly shifting flashes of light. The amount and intensity of sparkle depends on the quality of polish, as well as the size, shape, and symmetrical arrangement of facets.

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Seal

Plastic covering that provides a safeguard against loose diamonds being lost or damaged. Laboratory sealing has a number of security features including electrostatic security bars, pressure-sensitive transparent adhesive and cryptoprint text which only becomes visible after opening the seal.

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Shape

Name for the basic outline of a polished diamond. Examples of shapes are round, emerald , and pear.

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Simulant

Any material that is meant to look like or imitate a diamond, but is not a natural or synthetic diamond. Examples of diamond simulants: cubic zirconia, moissanite, and glass.

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Single-Cut

Diamond cut or shaped in an old-style cut with only 16 facets- 8 on the crown and 8 on the pavilion. This simple diamond cut is still used at times today for extremely small diamonds. Also known as an eight cut.

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Star Facets

Triangle shaped facets on a round brilliant cut diamond surrounding the table facet. When viewed as a whole, they resemble an 8-point star.

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Step Cut

A style of diamond cutting creating rows or steps of elongated facets, running parallel to the girdle on both the crown and the pavilion.

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Symmetry

Degree and regularity in shape and placement of facets, how well they align and relate to each other. Symmetry is very important to the life in a diamond, especially the brilliance; it affects how light is reflected and refracted in a diamond. Symmetrical round brilliant cut diamonds often display hearts & arrows.

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Synthetic Diamond

Man-made versions of the diamonds found in the earth. Synthetic diamonds have the same chemical structure and properties as natural diamonds, but are created in a laboratory in only a few days, instead of in the earth over billions of years - they sell at a much lower price. Click here to learn more about synthetic diamonds.

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Table

Large flat facet centered on the crown of a polished diamond.

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Table Size

Measure of the table width expressed as a percentage of the diameter. Table size is a proportion important to the balance between brilliance and dispersion.

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Tapered Baguette Cut

Diamond cut or shaped into a triangle with one corner cut off, and rows or steps of elongated facets running parallel to the girdle on both the crown and the pavilion. It is a modified version of a standard baguette cut.

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Tone

Degree or depth of colour in terms of lightness or darkness. The tone of a coloured diamond can range from very pale to very dark; it is the degree to which the colour of a diamond approaches white on the pale end, and black on the dark end.

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Toughness

Measure of brittleness, or resistance to fracture and breaking. Diamond has very good durability, but due to its directional hardness diamonds have certain planes of weakness along which they can split or break. Toughness and hardness together determine the durability of diamond.

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Transparency

Degree to which a diamond transmits light, directly relevant to the cloudiness or haziness of the actual diamond material, and the quality of the crystal. Click here to learn more about transparency and the DCLA Transparency Grading System.

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Treated Diamond

Diamonds that are artificially enhanced, to improve either colour or clarity. These treatments fundamentally alter the diamond from its natural state, and therefore need to be fully disclosed. Click here to learn more about treated diamonds.

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Trigon

Triangular shaped natural, with very fine triangular concentric lines. Trigons, when present, are a definitive indicator of natural diamonds.

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Trilliant

Diamond cut or shaped into a triangle, sometimes with curved sides.

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Twinning Line

Type of diamond inclusion that appears as a line or ribbon of pinpoints, tiny feathers, clouds, and crystals. Twinning lines are created where two rough diamonds have grown together in the earth under extreme heat and pressure.

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Upper-Girdle Facet

Triangle shaped facets lining the girdle on the crown of a diamond.

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Wavy Girdle

Girdle that is uneven in thickness and/or does not follow a straight plane around a diamond. A wavy girdle affects the symmetry grade of a diamond.

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World Federation of Diamond Bourses

International confederation of diamond bourses. The WFDB imposes strict rules and guidelines for ethical and professional conduct for the diamond trade on an international level.

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Yellow Diamond

A coloured diamond with a natural yellow body colour. Yellow must be the predominant colour, but it may be modified by shades of green, orange, or brown. The colour in natural yellow diamonds is created by the presence of nitrogen as an impurity when the diamond is growing. Natural yellow diamonds are common; canary diamonds are however more rare.

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latest news

Friday 22 August, 2014

GEM DIAMONDS REVENUE AT THREE YEAR HIGH

Gem Diamonds Ltd has had a 50 percent value increase this year. Rough diamond prices have risen about 14 percent year to date on Chinese demand.

Wednesday 6 August, 2014

GEM DIAMONDS RECOVERS 198 CT DIAMOND

Gem Diamonds recovered 198-carat the type IIa diamond at its Letseng mine at the end of July. The diamond a top white with no fluorescence will fetch an exceptional price when sold this later this year.

Monday 28 July, 2014

DIAMOND PRODUCTION UP BY 12% DE BEERS

Debswana in Botswana and De Beers Consolidated Mines in South Africa year to date production has increased by 12%.

Wednesday 16 July, 2014

FUNDING ZIMBABWE DIAMOND MINES RISKY

Rand Merchant Bank (RMB) a leading South African bank said diamond mining ventures in Zimbabwe are difficult to fund because of the high political risk and uncertainty in the country.

Monday 16 June, 2014

PETRA DIAMONDS DISCOVERS 122.5 CT BLUE DIAMOND

Petra Diamonds has found a 122.5 carat blue diamond at the Cullinan mine in South Africa.

This is the largest blue diamond found by Petra since the mine was sold to Petra by De Beers in 2008.

Monday 5 May, 2014

DCLA 13 YEARS OLD.

DCLA Australia's leading diamond grading laboratory has turned 13.

Thursday 3 April, 2014

DCLA SYNTHETIC DIAMOND IDENTIFICATION

DCLA Laboratory established in 2001 has always had the ability and equipment to identify synthetic diamonds.