Admire Diamonds

Diamond Talk

A diamond looks like any other rock until it is cut to produce maximum brilliance and fire. Here’s a glossary of terms commonly used with reference to cuts and properties.

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

Asscher Cut: Fancy diamond with the shape of a square emerald cut. Developed in early 1900 by Asscher, a diamond cutter from Amsterdam.

Baguette Cut: A step cut in the shape of a small rectangular diamond. May be tapered at one end.

Bearding: Tiny, numerous, hair-like fractures extending into the diamond.

Bezel: A facet on the crown, or upper part of the diamond above the girdle.

Blemish: Surface imperfection on a diamond.

Bort: Industrial grade diamonds, diamonds not suited as jewels.

Bow tie: An effect caused by a shadowy area visible in some fancy shapes, caused by light leaking out the bottom of the diamond.

Brilliant cut: The most common cut, round, containing 57 or 58 facets.

Bruise: An inclusion consisting of surface crumbling, accompanied by root-like feathers.

Carat: The metric ‘carat’, which equals 200 milligrams, is a standard unit of weight for diamonds and most other gems.

Carat Spread: The difference in weight between an ideally cut stone and a less perfectly cut stone with the same outer dimension (diameter at the girdle). Often used to help sell stones that are shallow cut, meaning the stone is short and fat, which makes the stone appear larger while weighing less.

Carbon Spots: A term sometimes used to describe the appearance of certain inclusions in a diamond.

Cavity: An inclusion consisting of a large or deep opening in a diamond.

Chip: A tiny missing piece, caused by normal wear and tear, or by cutting.
Clarity: A diamond’s relative position on a flawless to imperfect scale. The clarity scale goes from FL-IF to imperfect.

Cleavage: The propensity of crystalline such as diamond to split in one or more directions, either along or parallel to certain planes, when struck by a blow. Cleavage is one of two methods used by diamond cutters to split rough diamond crystals in preparation for the cutting process. Sawing is the other method.

Cloud: A group of tiny white inclusions which result in a milky or cloudy appearance.

Crown: Portion of the stone above girdle.

Crown Angle: The angle at which a diamond’s bezel facets (or, on emerald cuts, the row of concentric facets) intersect the girdle plane.

Culet: The facet on the bottom tip of the diamond. A diamond with no culet has a pointed tip. A diamond with a small to large culet has a flat surface at the tip. Culets can prevent chipping, but are less desirable when of the medium to large range. A diamond with a medium to large culet will appear to have a hole in the bottom when looking down on the stone, through the table.

Depth: The height of a diamond from the culet to the table. The depth percentage listed on the certification indicates the height of the diamond relative to the width measurement (height value, width value). A diamond which is too shallow or too deep will disperse light through the sides or the bottom instead of the top facet.

Emerald Cut: Step cut diamond, usually of rectangular shape and cut corners. The ideal length to width proportion of the emerald cut is between 1.5 and 1.7.

Eye clean: A diamond with no inclusions visible to the naked eye without the loupe.

Facet: A plane, polished surface of diamond. The brilliant, a full cut round diamond usually contains 58 facets.

Faceted Girdle: Some cutters also polish the girdle for maximal reflection, into 32 facets for a round diamond.

Fancy: A diamond with another than round cut (ie. princess, emerald, oval, etc.) and/or with an attractive natural body colour other than light yellow or light brown.

Feather: A separation or break due to either cleavage or fracture, often white and feathery in appearance.

Fluorescence: A bluish glow in high ultraviolet lighting conditions.

Girdle: The outer edge or the widest part of the diamond forming a band around the diamond. Some cutters also polish the girdle into facets for maximal reflection.

Grain: Small area of crystal structure distortion, usually associated with pinpoints.

Hardness: Mineral’s resistance to scratching on a smooth surface. Measured on the Mohs scale of relative hardness ranging from 1-10.

Hearts & Arrows Cut: A perfectly symmetrical round brilliant diamond with 58 facets. Under special illumination, the H&A cut diamond presents a pattern resembling hearts and a star of arrows of the same length and width.

Heartshape Cut: A type of fancy diamond cut, which is cut to resemble the popular Valentine’s Day shape.

Inclusion: Imperfection internal to the diamond, the unique ‘birth mark’ of a diamond. Inclusions are to be viewed with a 10x loupe and affect the diamond clarity. No two diamonds have the same position, size and colour of an inclusion.

Internal Graining: Internal indications of irregular crystal growth. May appear milky, like faint lines or streaks, or may be coloured or reflective.

Laser identification: Microscopically small superficial inscription created by a laser on a diamond for identification. Relatively easy to remove by polishing.

Marquise Cut: A modification of the brilliant cut, it is a boat shape, elliptical and pointed at both ends. It is sometimes described in old valuations as Navette.

Melee: Small diamonds under .20 carats, usually .10 carats

Mixed Cut: A stone with either the crown or pavilion cut as a brilliant cut, and the other part as a step cut.

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.

Oval Cut: Cutting shape of a diamond, oval with facets.

Pavillion: The lower portion of the diamond, below the girdle.

Pink: A rare natural fancy reddish colour. Radiation treated diamonds (not naturals) may also have a pink colour variation.

Points: Pts, 1 Pt. is a 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 parallel polished grooves produced by irregularities in the surface.

Polish Mark: Surface clouding caused by excessive heat (also called burn mark, or burned facet), or uneven polished surface resulting from structural irregularities.

Princess Cut: Normally a square stone with a faceted base. Resembles a brilliant cut except that the stone is square.

Radiant Cut: A type of brilliant cut fancy shape that resembles a square or rectangle with the corners cut off.

Ratio: A comparison of how much longer a diamond is than it is wide. Used to analyse the outline of fancy shapes only. Not applied to round diamonds.

River: Infrequently used reference for the colour of the diamond, ie River = D and E white. River + refers to colour D, exceptionally white.

Round 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 ‘brilliant’.

Rose Cut: Stone cut with a flat base, with the upper facets cut to point. Normally, encountered in antique jewellery starting the 17th century, but making a come back over the past few years.

Simulant: Any diamond-like material, natural or artificial, which is marketed as look-alike for a natural diamond, i.e. glass, zirconium, moissanite etc.

Single Cut: A very small round diamond with only 16 or 17 facets, instead of the normal 57 or 58 facets of a full cut round brilliant. Used mostly for pave jewellery.

Step Cut: One of the three styles of faceting arrangements with three concentric rows of facets arranged around the table and three concentric rows around the culet.

Surface Graining: Surface indication of structural irregularity. May resemble faint facet junction lines. Or cause a grooved or wavy surface, often cross facet junctions.

Symmetry: Describing small variations in a diamond’s symmetry, such as misalignment of facets or facets that fail to point correctly to the girdle. An indicator of the quality of a diamond’s cut, graded as either Ideal, Excellent, Very Good, Good, Fair or Poor.

Table: The flat facet on the top of the diamond. It is the largest facet on the cut diamond.


Table Percentage: The value which represents how the diameter of the table facet compares to the diameter of the entire diamond. A diamond with a 60% table has a table which is 60% as wide as the diamond’s outline.

Tone: A diamond 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, HPHT (high pressure high temperature) whitening, electromagnetic conduction whitening.

Wesselton: Originally the name of the diamond-mine producing white diamonds. Nowadays a less used reference for the colour of a diamond. Wesselton is H white. Top Wesselton  refers to colours F and G, some may call colour F a Top Wesselton +.