Diamond Glossary

Adamantine Luster The brilliant look of a diamond’s surface in reflected light.
Alluvial Diamond Mining The excavation mining of deposits which have been transported and concentrated by flowing water.
Argyle Diamond Mines The mining complex 2,400km north of Perth in Western Australia’s Kimberley Mountains.
Asscher Cut A square emerald cut with wide corners, a high crown, and a deep pavilion (see Diamond Shapes).
Baguette A small, rectangular to square step-cut diamond; sometimes tapered.
Beach Mining The extraction of diamonds from the section of a beach left uncovered between high and low tides.
Bearded Girdle A girdle with a rough finish.
Bezel Setting A thin strip of metal encircling a stone to secure it in a setting.
Black Diamond A very dark diamond which appears black and opaque due to numerous inclusions which block the transmission of light.
Blemish A term used by the GIA to describe a defect on the surface of a polished diamond.
Bow Tie Effect The dark area resembling a bow tie seen through the table across the centre of a marquise, oval or pear shape diamond.
Brilliance The intensity of the internal and external reflections of light from the crown of a polished diamond.
Canary Diamond A term used to describe an intensely yellow coloured diamond
Cape Series The diamonds ranging in colour from near-colourless to yellow (colour grading K to Z).
Carat Weight The weight of a diamond expressed in metric carats (see Diamond Characteristics).
Carbon Spot A misnomer for a black inclusion in a diamond.
Carré Cut A square step-cut diamond.
Champagne Diamond A light brown to dark brown coloured diamond, also called a cognac diamond.
Channel Setting The setting style in which diamonds are set between two parallel metal walls with no metal between them.
Clarity A diamond’s relative freedom from inclusions and blemishes (see Diamond Characteristics).
Claw Setting A set of narrow metal supports, also known as prongs, to hold a diamond.
Cognac Diamond A light brown to dark brown coloured diamond, also called a champagne diamond.
Colour Grade The relative position of a diamond’s body colour on a colourless-to-light-yellow scale (see Diamond Characteristics).
Crown The part of the diamond above the girdle, i.e. the top of the diamond.
Crown Height The distance between the girdle and the table of a diamond.
Crown Height Percentage The distance between the girdle and the table of a diamond, expressed as a percentage of the average girdle diameter.
Culet A small facet on the point of the pavilion of a brilliant cut diamond, i.e. the point at the bottom of the diamond.
Cushion Cut A modified brilliant cut diamond with curved sides and rounded corners (see Diamond Shapes).
Cut The relative proportions and finish of a polished diamond (see Diamond Characteristics).
Depth The dimension of a diamond from the table to the culet of a diamond.
Diameter The distance from one edge of the girdle on a diamond to the opposite edge.
Diamond A mineral composed of carbon crystallized at extremely high pressures and temperatures.
Diamond Certificate A report written by a grading laboratory, such as the Gemological Institute of America (see Diamond Certification).
Dispersion The separation of white light into spectral colours.
Emerald Cut A rectangular step cut with diagonally cut corners (see Diamond Shapes).
Facet A flat polished surface on a finished diamond.
Faceted Girdle A girdle which has been polished with a series of flat facets.
Fancy Coloured Diamond Any naturally coloured diamond with a noticeable depth of body colour considered to be rare, i.e. pink or blue.
Fancy Cut Any diamond cut, or shape, other than a round brilliant cut (see Diamond Shapes).
Finish The quality of a diamond’s polish, the condition of the girdle and the precision of the cut.
Fire the rainbow prism of light that is reflected from a polished diamond, technically known as “dispersion”. The better a diamond is cut, the more fire is emitted from the diamond.
FL Flawless, the clarity grade applied to diamonds with no internal or external blemishes or inclusions.
Florescence the emission of visible light by a diamond when stimulated by high energy light such as UV light. Fluorescence rarely affects a diamond's sparkle and brilliance, and in warmer or lower coloured diamonds, fluorescence makes them look whiter or more colourless.
Four C’s the four characteristics which determine the quality and value of a diamond: cut, colour, clarity and carat weight (see Diamond Characteristics).
Gemological Institute of America (GIA) a non-profit educational institution, established in 1931 to serve the diamond industry and the public. The grading scales developed by the GIA have become the standards for diamond grading all over the world.
Girdle narrow band which surrounds the edge of a diamond separating the crown (top) from the pavilion (bottom).
Grain Setting the setting style in which small diamonds are held in place with small beads of metal.
Hardness diamond’s resistance to scratching and abrasion.
Heart Shape modified brilliant cut in the shape of a heart (see Diamond Shapes).
Internally Flawless the clarity grade applied to diamonds with no internal blemishes or inclusions.
Inclusion an internal characteristic of a diamond otherwise referred to as a blemish.
JAA Jeweller’s Association of Australia.
Laser Drilling an enhancement process used to improve the appearance of diamonds which contain dark inclusions.
Laser Inscription an identifying number or message engraved on a diamond (usually on the girdle) using a laser.
Length-to-Width Radio the comparison of the length and width of the girdle outline when viewing a non-round shaped diamond from above, determined by dividing the length by the width (the width is expressed as 1).
Loupe a small magnifying lens used to examine a diamond.
Luster the appearance of the surface of a polished diamond in reflected light.
Marquise Cut a modified brilliant cut boat-shaped diamond with curved sides and pointed ends (see Diamond Shapes).
Modified Brilliant Cut a diamond cut based on the round brilliant cut, but with either more or fewer facets than the standard 58 (or 57).
Near-Colourless the term used to describe diamonds which appear colourless when viewed from above.
Old Mine Cut an early form of a brilliant cut diamond with a nearly cushion shape girdle outline when viewed from above, a high crown, a small table, a deep pavilion, and a large culet.
Open Pit Mining the diamond mining process involving excavation by digging a pit.
Oval Cut a modified brilliant cut diamond with an elliptical girdle outline when viewed from above (see Diamond Shapes).
Pavé Setting the setting style in which many small gemstones are placed close together.
Pavilion the portion of the polished diamond below the girdle, ie. bottom section of the diamond.
Pavilion Depth the distance between the girdle and the culet of a diamond.
Pavilion Depth Percentage the distance between the girdle and the culet of a diamond, expressed as a percentage of the average girdle diameter on round brilliant cuts, and as a percentage of the width on non-round shaped diamonds.
Pear Shape a modified brilliant cut with one rounded end and one pointed end which has a pear shaped girdle outline when viewed from above (see Diamond Shapes).
Piqué French meaning “pricked”. A European clarity grading abbreviated to P1, P2 and P3, applied to diamonds with inclusions visible to the naked eye. The GIA clarity grade equivalents are I1, I2 and I3.
Plotting the process of recording the type, location, size and shape of clarity characteristics of a diamond on a facet diagram.
Polish the condition of the facet surfaces on a polished diamond.
Polished Girdle a girdle which has been finished to a smooth surface.
Princess Cut a square modified brilliant cut usually with 57 facets (see Diamond Shapes).
Proportions the relative dimensions and angles of a polished diamond and the relationship between them.
Quality the relative excellence of a diamond’s cut, colour and clarity.
Radiant Cut a square or rectangular modified brilliant cut with the corners trimmed (see Diamond Shapes).
Reflection the bouncing back of light when reflected from a polished diamond’s surface.
Rose Cut an old cut characterized by a flat base, a circular girdle, a pointed domed crown and a varying number of triangular facets.
Rough Diamond a diamond as it is recovered from the earth prior to undergoing cutting and polishing.
Round Brilliant Cut the standard round cut diamond with a circular girdle and 57 or 58 facets as it may or may not have a culet (see Diamond Shapes).
Scintillation the sparkles and flashes that a diamond produces when it is tilted or rotated in the light giving a diamond its beauty.
Shape the girdle outline of a diamond when viewed from above.
Single Cut a cutting style with a circular girdle, a table, eight crown facets and eight pavilion facets.
SI Slightly Included, clarity grading for diamonds (see Diamond Characteristics)
Solitaire a ring with a single diamond.
Step Cut a cutting style in which long, narrow, four-sided facets are arranged in rows parallel to the girdle on both the crown and the pavilion, eg. Emerald cut or baguette cut.
Stone a diamond industry term for any polished diamond.
Sub-Level Caving an underground diamond mining method in which ore drilled and blasted loose at one level is dropped through a slot to a level below, there to be collected and transported to the surface.
Symmetry the grading term for the exactness of shape and placement of facets.
Table the large facet in the centre of the crown of a polished diamond.
Table Diameter the distance between any two opposing sides of the table on a round brilliant cut diamond.
Table Percentage for round brilliant cuts, the size of the table expressed as a percentage of the average girdle diameter.
Tapered Baguette a modification of the rectangular baguette in which one end is narrower than the other.
Total Depth Percentage the depth from the table to the culet, expressed as a percentage of the average girdle diameter of a round brilliant cut, and as a percentage of the girdle width on non-round diamonds.
Trilliant Cut a modified brilliant cut with a triangular girdle outline when viewed from above.
Underground Mining a process of mining diamonds by excavating horizontal or vertical tunnels and bring the ore and associated minerals to the surface.
Under Rail the bar(s) of metal beneath the centre setting of a ring.
VS Very Slightly Included, clarity grading for diamonds (see Diamond Characteristics).
VVS Very Very Slightly Included, clarity grading for diamonds (see Diamond Characteristics).

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