Antique and other old or heavily used diamonds can have abrasions, tiny nicks along facet junctions, producing white fuzzy lines instead of sharp crisp facet edges.
Acronyms of D.I.A.M.O.N.D. include Defense Intrusion Analysis & Monitoring Desk, Development and Integration of Accurate Mathematical Operations in Numerical Data-Processing, and Dow Industrial Average Model New Deposit Shares.
Amsterdam, was a major diamond cutting center in the nineteenth century, but lost almost all its gem cutters to Antwerp, due in part to strict working conditions imposed on the Dutch diamond-cutting factories by labour unions in the prewar years.
A 102.29 carat cushion cut diamond certified by the GIA as Fancy Vivid Yellow, VS2 clarity.
Many diamonds are sourced from alluvial deposits in existing or previous river beds. Alluvial diamonds are usually of gem quality, probably because lower grade stones would have been damaged or destroyed.
To achieve maximum brilliance, there are many angles which are important in diamond cutting. Angles determine proportion.
Diamonds were discovered in Angola in 1913. Since 25 years of civil war ended in 2002, Angolan production should be important, but there are still problems. Although Angola is rich in gem quality diamond deposits, its output has been variable following long periods of civil war or other armed conflict.
Appraisal is carried out on rough and polished diamonds at many stages to asses quality and market values.
Arrows and Hearts
An optical pattern discernable in some well-proportioned diamonds, and marketed as a demonstration of excellent cutting.
A rectangular or oblong step or trap cut used for diamonds and other gemstones.
A typical diamond FAQ is “where do the best diamonds come from”. There is no single quick answer, apart from the slightly facetious “in the ground”. We are in process of preparing a more complete answer which will be linked from here when ready.
The second most active diamond prospecting company after De Beers. Owns the Ekati mine in Canada, producing 4% and 6% of world’s diamonds by volume and value respectively. Markets using Canada Mark brand name.
“Black diamond” is a term used in American ski resorts to designate a steep slope or one which involves challenging terrain. So called because the marker signs show a black diamond (lozenge) shape on a white background.
An external mark or imperfection on a diamond, implicitly only slight and capable of being removed.
Originally describing near white diamonds with strong blue fluorescence, often misleadingly used or abused term to confer the idea of whiter than white.
White light captured from all the surfaces of the diamond and reflected up through the top. A diamond with the correct proportions yields the highest brilliance.
A has triangular facets that surround the stone that culminate on a flat top. A can be round, marquise, oval, pear-shaped, heart-shaped, princess (square), or radiant.
An inclusion consisting of surface crumbling, often accompanied by tiny, root like feathers.
A unit of weight for diamond equivalent to 200 milligrams.
Diamonds are composed entirely, or almost entirely, of carbon.
An inclusion consisting of a large or deep opening in the diamond.
The smallest facet at the bottom of the diamond.
The tendency of a crystallized mineral to break along certain definite directions producing more or less smooth surfaces. We prefer Karolina Kurkova’s cleavage.
Clarity is graded on a scale that ranges from Flawless (FL) to Imperfect (I3). A diamond’s relative position on a flawless to imperfect scale. Clarity characteristics are classified as inclusions (internal) or blemishes (external). The size, number, position, nature, and color or relief of characteristics determines the clarity grade. Very few diamonds are flawless, that means, show no inclusions or blemishes when examined by a skilled grader less than 10X magnification. If other factors are equal, flawless diamonds are most valuable.
Diamond ring or other jewellery containing a number of diamonds. Also a number of kimberlitic pipes occurring in close proximity.
A proprietary machine for grading diamond color.
The color of a diamond has the second biggest impact on its price, after carat weight. Did you know that diamonds come in every color of the Rainbow? Describes the “yellowness” of a stone. The color scale ranges from D (colorless) to Z (deep yellow). Grading color in the normal range involves deciding how closely a diamond’s body color approaches colorlessness. Most diamonds have at least a trace of yellow or brown body color. With the exception of some natural fancy colors, such as blue, pink, purple, or red, the colorless grade is the most valuable.
The top portion of a diamond, from the girdle (the thickest part around the stone) to the table.
An inaccurate term used by some people in the jewelry industry to describe the appearance of certain inclusions in a diamond. The term refers to included crystals that have a dark appearance, rather than a white or transparent appearance, when viewed under a microscope. In most cases, these dark inclusions are not visible to the naked eye, and do not affect the brilliance of the diamond.
A diamond colored by a surface coating which masks the true body-color; the coating may be extensive (entire pavilion, for example), but is more often limited to one or two pavilion facets or a spot on the girdle.
Perhaps one of the most misused of the 4 C’s, it refers to the style of cut (brilliant, emerald), the shape of the stone (round, heart-shaped), and the geometric proportions to which the diamond is cut.
The point or small facet on the bottom of most round or brilliant cut diamonds, as opposed to a keel on other cuts.
The height of a diamond, measured from the culet to the table.
A crystal made up of 99.95% pure carbon atoms arranged in an isometric, or cubic, crystal arrangement. It is this unique arrangement of the carbon atoms that makes diamond look and behave differently from other pure carbon minerals such as graphite (the soft black material used to make pencils).
The method by which a rough diamond that has been mined from the earth is shaped into a finished, faceted stone. As a first step, cleaving or sawing is often used to separate the rough into smaller, more workable pieces that will each eventually become an individual polished gem.
An instrument that is used to measure a diamond’s length, width and depth in millimeters
“Double Diamond” is an American skiing term for an extreme, expert-only ski slope, designated by a sign with 2 black diamonds. Also known as a double black diamond. Double Diamond is also the name of an English beer.
Diamond is one of the hardest, toughest, and most durable of substances.
Also called “single cut”. Diamonds, usually small, with only 18 facets instead of the full 58 on a brilliant cut.
Eppler devised the specifications for this “Practical Fine Cut” in 1939.
No visible inclusions with the naked eye, therefore at least SI in clarity.
The name of a famous diamond.
An emerald cut is more “glassy” in appearance, since its facets usually span the length or width of the stone. Emerald cuts are different from step cuts in that their corners are rounded.
A GIA and HRD-CGL grade for excellent cut and polish of brilliants.
A facet placed without regard for symmetry and not required by the cutting style.
The flat polished surfaces on a diamond. s have 58 triangular facets and therefore “sparkle” more than emerald cuts, which have far fewer facets and therefore have a more “glassy, elegant” look.
A diamond with an attractive natural body color other than light yellow or light brown.
A separation or break due to either cleavage or fracture, often white and feathery in appearance.
An imperfection of a stone.
When light is refracted within the diamond, the result is that multi-colored light beams out of the table, and it somewhat looks like fire. For maximum fire, seek out a well-proportioned stone.
A bluish glow within the diamond when exposed to ultraviolet light. Some people like fluorescence and some don’t. In any case, strong fluorescence should be avoided.
With 58 facets, i.e. usually a brilliant cut, and usually round.
Gemological Association and Gem Testing Laboratory of Great Britain. Now Gem-A.
Manufacture and market “Gemesis Cultured Diamonds, based in Sarasota, Florida, USA.
A person with expertise in gemology, a gemstone expert. There are formal qualifications, such as F.G.A. (Fellow of the Gemological Association) in the UK.
Any organic or inorganic mineral or material, excluding metal, which is used to decorative effect in jewellery. Some argue that only natural, rare or valuable items should be included.
Gemological Institute of America. Reliable diamond certification. Diamond research.
The narrow band around the width of the diamond, where the crown and pavilion meet.
A small area of concentrated crystal structure distortion, usually associated with pinpoints.
Any of the facets adjacent to the girdle on a brilliant cut or other diamond, split into upper (crown) girdle facets, and lower (pavilion) girdle facets.
The measurement describing the percentage of the diamond’s average girdle diameter.
Sometimes called a “certificate”, although labs do not “certify” diamonds. The grading report, issued by an independent laboratory, should accurately describe the proportions, weight, color, clarity, symmetry, polish and possible fluorescence seen in the diamond being evaluated. Some labs such as GIA and AGS are felt by many experts to be more consistent and stringent in their grading than some other labs.
The largest faceted diamond in the world, weighing 545.67 carats.
The process of appraising a diamond, and allocating grades to it.
Mineral’s resistance to scratching on a smooth surface. Mohs scale of relative hardness consists of 10 minerals, each scratching all those below it in scale and being scratched by all those above it.
Hearts and Arrows
A general term when referring to diamonds with a percise and complete pattern of hearts and arrows achieved by perfect cutting proportions.
There are various ways of considering the highest price paid for a diamond, total price, per carat price, and relative price in today’s money. We will be adding a highest priced diamond page.
Pure, spectral (prismatic) color. Hues include gradations and mixtures of red, organdy, yellow, green, blue, violet and purple.
IGI, I.G.I., International Gem Laboratory
Organization with laboratories located in the heart of the gem & jewelry districts throughout the world, including New York, Antwerp, Mumbai, Bangkok and Tokyo.
Theoretically perfect cutting proportions for (round brilliant cut) diamonds. Exact specifications vary. Many mathematical models ignore girdle thickness.
Anything other than diamond which imitates diamond. Other words used include simulant and fake. It is important to note that synthetic diamond is real diamond. An imitation can be natural or synthetic.
A large diamond weighing 890 carats in its rough state, 407.48 carats polished, the third largest diamond ever cut.
The name of a ray of light as it enters a diamond, or change of medium.
Integrity is important in most business to business markets, and the commercial diamond market is said to operate with integrity. Some proponents of the Kimberley Process speak about the integrity of diamond itself, as though this had ever been questioned.
Internally Flawless ( IF )
A clarity grade which allows for naturals or other surface features or imperfections.
The International Diamond Manufacturers’ Association was formed at the end of World War II, and first met in Antwerp in 1946.
A mineral crystal contained in a diamond. Inclusion: Imperfection internal to the Diamond.
Internal indications of irregular crystal growth. May appear milky, like faint lines or streaks, or may be colored or reflective.
A diamond which has been exposed to radiation.
Diamond is one of the isomers of carbon. Isomers are molecules which have the same molecular formulae but different molecular structures.
A description of the color of certain green diamonds.
Diamonds are not necessarily jewellery, and vice versa, but diamond jewellery accounts for the bulk of diamond demand and sales by value, and is an important section of the jewellery market.
A shape of diamond cut with 8- facets. A large (245 carats) and famous diamond, originally called the Reitz diamond. Renamed when it was recut in 1897 during Queen Victoria’s diamond jubilee year.
A diamond enhancement technique whereby a laser is used to drill to an inclusion which is then bleached to enhance the diamond’s appearance.
Laser Drill Hole
A tiny tube created in a diamond by laser drilling, which is often done to treat diamonds.
A small magnifying lens used to examine diamonds. 10x magnification is the standard.
Indicating that a diamond contains no visible inclusions when using the industry standard magnification of ten times (10x).
The facets on the pavilion of a round brilliant just below the girdle.
The luster of a diamond is its highly reflective surface sheen due to its high refractive index combined with the highly polished surfaces.
A color description used for certain pinkish purple diamonds.
A large famous diamond, made even more famous by the audacious attempt to steal it and other diamonds from the Millennium dome exhibition.
Some over-fluorescent diamonds have a cloudy or milky appearance, especially in ultra-violet light or daylight.
A place where diamonds are extracted from the ground, by either open cast or deep pit mining.
The extraction of diamonds from in-ground deposits, as compared with dredging or other recovery methods.
Mine Cut Diamond
An early form of the brilliant diamond with a squarish-shaped girdle, high crown, small table, deep pavilion, and very large culet.
Modern Brilliant Cut
A diamond normally with 58 facets including the culet, polished using relatively modern theory, but not necessarily ideal or near ideal proportions, usually round unless otherwise stated.
Modified Brilliant Cut
A diamond cut in a shape or style other than round, such as oval, pear, marquise, heart, princess, radiant, or trilliant. Could also be applied to round stones based on the brilliant cut.
The 10-point scale of mineral hardness. Diamond scores 10 on Mohs Scale. The diamond is the hardest of all known natural substances.
A piece of jewellery into which a diamond is set.
Person who makes the piece of jewellery into which gemstones will be set by a setter.
A descriptive term used by some mines or producers in preliminary sorting of rough diamonds.
These blemishes can be found on some polished diamonds when some of the rough is left on the diamond. This is often done so the cutter can maximize weight in a diamond.
A thin, sharp looking inclusion in a diamond.
Diamond Nexus Labs of Franklin, Wisconsin misleadingly describe diamond stimulants on their website as synthetic diamonds, and make numerous other dodgy claims.
Used as a solvent and catalyst in production of synthetic diamonds.
Diamonds have traditionally been sorted in north light, often before midday, as this is considered to be a consistent color, although special standardized diamond sorting lighting is now available and in common use.
A solid figure having eight sides or faces. A rough diamond with this approximate shape. The commonest crystal formation of diamond.
Any cut, usually round, predating the modern brilliant cut in style.
Old European Cut Diamond
The earliest known form of brilliant cut diamond with a very small table, heavy crown and large depth.
A weight of one fifth of a gram. Any diamond of this weight.
Culet which has been polished into a facet rather than being left as a point.
A fancy shape of diamond, usually a modified brilliant cut.
Important jewellery metal, used in high quality alloys of platinum and white gold.
From French, literally paved. Diamonds are other gemstones set in such a way that they substantially cover a surface of a piece of Jewellery.
The angle between the main pavilion facets and the girdle. In diamond cutting and proportion, this is the single most important dimension, and should be around 40.75° to 41°.
Any of the facets on the pavilion of a diamond, but usually referring to the main pavilion facets, as distinct from the lower girdle facets.
The bottom portion of a diamond, from the girdle (the thickest part around the stone) to the culet.
Some diamonds and other gemstones and minerals continue to glow or emit visible light for a period of time after exposure to visible, ultra-violet or other light, after the light source has been removed.
The emission of visible light by a diamond due to the incidence of light of a different wavelength, including fluorescence and phosphorescence.
Silvery gray precious metal often used for setting or mounting high quality diamonds as Jewellery.
A very small white dot on the surface of the stone. By far, the most common flaw that can be found on a diamond.
The final smoothness of the surfaces of a diamond. An excellent polish will result in a lower-weight stone, so most diamond cutters will make tradeoffs.
Surface clouding caused by excessive heat (also called burn mark, or burned facet), or uneven polished surface resulting from structural irregularities.
American word for claw, as in gem setting.
The consideration of the overall shape of a diamond taking each part in relation to all other parts. An important quality element for diamonds.
Another word of Clarity.
As De Beers adverts state, it is as important in a diamond as anything else you own.
Radiant cuts combine the best of brilliant cuts, with a square emerald cut outline.
Important optical effect, whereby light bounces off a surface.
Important optical effect, the deviation of light when it passes from one medium to another, e.g. air to diamond. See Refractive index.
A grainy or pitted girdle surface, often with nicks.
Rhodium is a highly reflective silvery precious metal, one of the platinum group of metals, often used to plate over “white” gold alloys to enhance their whiteness, in and around diamond settings. Not usually needed on platinum.
Round Brilliant Cut
The most common cut containing 58 facets. Also the most , in terms of most efficient use of light to increase brilliance and fire, hence the name.
The process of fixing a gemstone into a mount to create a piece of jewellery. A setting is a word used by consumers to describe what a jeweler would call a mount. The word setting is sometimes used in referring to a collet.
Refers to the way that the stone is cut. Common shapes are: Round, marquise, oval, pear-shaped, heart-shaped, princess (square), and radiant (also square).
White highly reflective metallic element, used in Victorian times for diamond setting, before the development of white gold alloys, and before platinum could be isolated.
An obsolescent color grading term denoting diamonds whiter, or less yellow than light cape.
A ring or other piece of jewellery containing a single diamond, or sometimes a single major diamond with smaller diamonds as embellishments.
The combination of brilliance and fire that emanates from the diamond.
An step cut diamond is “glassy” in appearance, since its facets usually span the length or width of the stone.
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. Single cuts are occasionally used for pave jewelry and other jewelry that utilizes numerous small diamonds set closely together.
A linear indentation normally seen as a fine white line, curved or straight.
Surface indication of structural irregularity. May resemble faint facet junction lines, or cause a grooved or wavy surface, often cross facet junctions.
Halfway between a brilliant and an eight cut, with 34 facets in total.
The largest surface on a diamond, located on the top of the diamond facing the viewer. The table culminates the crown of the diamond.
Table Percentage (%)
The width of the table divided by the diameter of the diamond. The table percentage is one of the many metrics used to measure how well proportioned a diamond is cut, and consequently how much “sparkle” it will have.
Usually describing a girdle, and often expressed as a percentage of the height or depth of the diamond, often using relative terms such as “medium”.
An aspect of color, important in grading fancy coloured diamonds.
Also known as step cut. A traditional way to cut rectangular, octagonal or other non-round diamonds, including emerald cuts. Looses brilliance compared with more modern brilliant cut styles.
A diamond with a body color induced by some form of artificial irradiation, often in conjunction with controlled heating (known as annealing).
The name of Werner Herzog’s film about British engineer Graham Dorrington’s air-ship expedition over Guyana.
Refers to the overall finish of the diamond, including the polish on the facets, the symmetry of facets with respect to each other, and the shape of the culet.