Diamond Education Glossary of Terms
To further help you with your diamond education, Diamond Exchange has compiled this useful glossary of terms commonly used when dealing with diamonds and precious stones.
The brilliant look of a diamond’s surface under reflected light.
A girdle with a rough finish.
A term used by the GIA to describe a defect on the surface of a polished diamond.
A term used to describe an intensely yellow-coloured diamond.
A misnomer for a black inclusion found in a diamond.
The setting style in which diamonds are set between two parallel metal walls with no metal in between.
A light to dark brown coloured diamond, also called a Champagne Diamond.
The distance between the girdle and the table of a diamond.
The distance from one edge of the girdle on a diamond to the opposite edge.
The separation of white light into spectral colours.
A girdle that has been polished with a series of flat facets.
The quality of a diamond’s polish, the condition of the girdle and the precision of the cut.
The emission of visible light by a diamond when stimulated by high energy light such as UV. Fluorescence rarely affects a diamond’s sparkle and brilliance, and can make warmer/lower-coloured diamonds look whiter and more colourless.
Narrow band which surrounds the edge of a diamond separating the crown (top) from the pavilion (bottom).
The Jeweller’s Association of Australia.
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).
An early form of a brilliant cut diamond with a nearly cushion-shaped girdle outline when viewed from above, a high crown, a small table, a deep pavilion and a large culet.
The setting style in which many small gemstones are placed closely together.
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.
The process of recording the type, location, size and shape of clarity characteristics of a diamond on a facet diagram.
A diamond as it is recovered from the earth prior to undergoing cutting and polishing.
The girdle outline of a diamond when viewed from above.
A ring that usually has a single diamond.
An underground diamond mining method in which ore drilled and blasted loose at one level is then dropped through a slot to a level below, there to be collected and transported to the surface.
The distance between any two opposing sides of the table on a round brilliant cut diamond.
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.
The bar(s) of metal beneath the centre setting of a ring.
The excavation mining of deposits which have been transported and concentrated by flowing water.
A small, rectangular-to-square step cut diamond that is sometimes tapered.
A thin strip of metal encircling a stone to secure it in a setting.
A dark area resembling a bow-tie that can be sometimes seen through the table across the centre of a marquise, oval- or pear-shaped diamond.
The range of diamonds that fall in the near-colourless to yellow colour grades (K to Z).
A square step-cut diamond.
The distance between the girdle and the table of a diamond, expressed as a percentage of the average girdle diameter.
A mineral composed of carbon crystallised at extremely high pressures and temperatures.
Any naturally coloured diamond with a noticeable depth of body colour that is considered to be rare, i.e. pink of blue.
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.
The setting style in which small diamonds are held in place with small beads of metal.
The clarity grade applied to diamonds with no internal blemishes or inclusions.
An enhancement process used to improve the appearance of diamonds that contain dark inclusions.
A small magnifying lens used to examine a diamond.
A diamond cut based on the round brilliant cut, but with either more or less facets than the standard 58 (or 57).
The diamond mining process involving excavation by digging a pit.
The portion of the polished diamond below the girdle, i.e. the bottom section of the diamond.
The condition of the facet surfaces on a polished diamond.
The relative dimensions and angles of a polished diamond and the relationship between them.
The bouncing back of light when reflected from a polished diamond’s surface.
A cutting style with a circular girdle, a table, eight crown facets and eight pavilion facets.
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, i.e. Emerald cut or Baguette cut.
The grading term for the exactness of shape and placement of facets.
For round brilliant cuts, the size of the table expressed as a percentage of the average girdle diameter.
A modified brilliant cut with a triangular girdle outline when viewed from above.
The mining complex 2,400km north of Perth in Western Australia’s Kimberley Mountains.
The extraction of diamonds from the section of a beach that is left uncovered between high and low tides.
A very dark diamond that appears black and opaque due to numerous inclusions, which block the transmission of light through, within and out of the diamond.
The intensity of the internal and external reflections of light from the crown of a polished diamond.
A light to dark brown coloured diamond, also called a Cognac Diamond.
A set of narrow metal supports, also known as prongs, that holds the diamond in place.
The part of the diamond above the girdle, i.e. the top of the diamond.
A small facet on the point of the pavilion of a brilliant cut diamond, i.e. the point at the bottom of a diamond.
The dimension of a diamond from the table to the culet of a diamond.
A report written by a grading laboratory, such as the Gemological Institute of America. (For more details, refer to Diamond Certificates.)
A flat polished surface on a finished diamond.
The clarity grade applied to diamonds with no internal or external blemishes or inclusions.
A non-profit educational institution that was established in 1931 to serve the diamond industry and the public. The GIA’s grading scales have become the standard for diamond grading all over the world.
A diamond’s resistance to scratching and abrasion.
An internal characteristic of a diamond, otherwise referred to as a blemish.
An identifying number or message engraved on a diamond (usually on the girdle) using a laser.
The appearance of the surface of a polished diamond under reflected light.
The term used to describe diamonds which appear colourless when viewed from above.
The distance between the girdle and the culet of a diamond.
A French word, meaning ‘pricked’. A European clarity grading system abbreviated to P1, P2 and P3, and is applied to diamonds with inclusions visible to the naked eye. The GIA clarity grade equivalents are I1, I2 and I3.
A girdle that has been finished to a smooth surface.
The relative excellence of a diamond’s cut, colour and clarity.
An old cut characterised by a flat base, a circular girdle, a pointed domed crown and a varying number of triangular facets.
The sparkles and flashes that a diamond produces when it is tilted or rotated in the light, giving a diamond its beauty.
A diamond industry term for any polished diamond.
The large facet in the centre of the crown of a polished diamond.
A modification of the rectangular baguette in which one end is narrower than the other.
A process of mining diamonds by excavating horizontal or vertical tunnels and bringing the ore and associated minerals to the surface.