A to Z of Diamonds Glossary

Diamonds Index

Round Brilliant Cut Diamond

Cachet	An indication of approved or superior status, "seal of approval", also sometimes used for cachette. Both from French cacher, to seal.
Cachette	A sealed packet containing diamonds bought in a trade deal, together with agreed payment terms.
Cairo Star	Variation on the modern round brilliant cut with 74 facets.
Canada	Diamond prospecting started in Canada in the 1960's or earlier, kimberlite was found in the 1990's, and the first commercial mine opened in 1991. Canada now produces over 12 million carats annually worth over $2 billion according to some sources.
Canary	Popular name for a vivid fancy yellow diamond.
Cape	Originally Cape Colony in South Africa, also the almost obsolete name of a yellowish colour, corresponding to GIA grades O, P,and Q. The entire series from near E to Z colours are known as the cape series.
Carat, Carats	Defines and explains the terms carat and carats as applied to diamonds other gemstone and gold alloys.
Carat Weight	The weight of diamonds is measured in carats, a metric carat being a fifth of a gram.
Carbon	Diamonds are composed entirely, or almost entirely, of carbon.
Carbon Spot	A misnomer. As diamonds are composed almost entirely of carbon, any black spots in them are unlikely to be carbon.
Carbonado	Imperfectly or partially crystalised diamond.
Carnegie Institution Geophysical Laboratory	In 2004, the Carnegie Institution's Geophysical Laboratory announced it could produce large gem quality diamonds 100 times faster than previously.
Cartel	De Beers appears to have operated a cartel for most of its existence.
Cartier	A well known jeweller, and also the previous name of the Taylor Burton diamond.
Cavity	A hole or void in a diamond or other gemstone, either internal or extending to the surface. Internal cavities may naturally contain gas, liquid, solid, a combination of two or three of these, and there may be phase changes depending on ambient temperature.
Cecil Rhodes	A financier, statesman, colonialist, and British imperialist. He formed De Beers, acquired and maintained a near monopoly on diamond mining and production, which still endures over 130 years later.
Celebrity, Celebrities	Although many celebrities have owned or been connected with impressive or famous diamonds in the past, there is a modern trend for diamonds to be lent out to celebrities in return for the media attention which the pairing can attain, in a similar manner to designer couture.
Centenary	A large and famous diamond, unveiled in 1988 for the centenary of De Beers. 599 carats in the rough, it was cut to a gem weighing over 273 carats. It is remarkable also for being D colour, and second only to the Cullinan for its combination of size and quality.
CERN, C.E.R.N., European Centre for Nuclear Research	CERN - CVD Diamond Radiation Detector Development. "Diamond is a material with such extraordinary physical properties that we wish to explore its use as a particle detector".
Certificated	A diamond which has been graded and certified or certificated by a gemmological laboratory.
Certificates, Certification	Documents issued by gem labs attesting the genuineness and stating the quality of a diamond or other gemstone.
Certified	A diamond which has been laboratory graded, and certified as to quality. We offer certified diamonds for sale.
Chameleon	Name for rare colour change diamonds.
Champagne	Apart from the world famous French origin-marked sparkling wine sparkling wine, champagne is used rather romantically to describe diamonds which might otherwise to considered to be a slightly "off" colour.
Channel Setting	A setting style or method where there is no metal showing between stones. In our opinion, better avoided unless very well executed.
Chard	Owner and operator of this website.
Cheap	A word which is not usually associated with diamonds or jewellery. It is considered to have negative connotations.
Chemical Vapour Deposition	Synthetic diamond can be made by the CVD process. First achieved in 1952 by William Eversole of Union Carbide Corporation of the USA.
Chemistry	All diamonds are composed of carbon, although most have tiny amounts of impurities.
Chiffre	A rose cut with three facets each of which has a curved outer edge, forming an equilateral curved triangle, similar to the rotor shape of a Wankel engine.
China	Only relatively recently has China located and started to extract diamonds. It is also a growing cutting centre, and it may in the next few years be the biggest consumer growth demand area.
Chip, Chips, Chippings	Chips were possibly invented in Belgium, and are served with mayonnaise. We explain that Chip, Chips, and Chippings are words which are usually not applied to diamonds.
CIBJO	Confédération International de la Bijouterie, Joaillerie, Orfèvrerie des Diamantes, Perles et Pierres, in English International Confederation of Jewellery, Silverware, Diamonds and Stones. A world jewellery confederation.
Clarity	The clearness, purity, absence, or presence of inclusions in a diamond.
Clarity Enhanced, Clarity Enhancement	The "improvement" in the apparent clarity of a diamond usually by filling surface cracks with glass. Not recommended.
Clean	An word used informally to mean flawless, or at least to infer flawlessness.
Cleaning	At the mines, diamonds are cleaned using a mixture of methods, including boiling in acid. For domestic cleaning of diamonds or other jewellery, warm soapy water works well. Ultrasonic cleaning tanks can be used with care.
Cleavage	The tendency of a crystallised mineral to break along certain definite directions producing more or less smooth surfaces. We prefer Karolina Kurkova's cleavage.
Cleavages	A term used when sorting rough diamonds, referring to irregularly shaped or broken crystals.
Cleaving	Method of splitting a diamond along a grain.
Cloud	Area with many microscopically small inclusions but which impair clarity.
Cloudy	Some low clarity diamonds with significant cloudy or milky areas get sold to consumers with a limited knowledge.
Closed Culet	A culet which consists of a point rather than a facet.
Club	Nowadays diamond clubs and bourses tend to be interchangeable. Originally, a diamond club was primarily a place to trade rough diamonds, and a bourse was for polished goods.
Cluster	Diamond ring or other jewellery containing a number of diamonds. Also a number of kimberlite pipes occurring in close proximity.
Coated, Coating	Many rough diamonds are covered by a skin or coating which can mask their potential appearance.
Coating, Applied	Diamonds have sometimes had a coloured coating applied to them for fraudulent purposes. In recent years, new high-tech coating methods have appeared.
Cognac	A somewhat romanticised name for a slightly brownish diamond colour.
Color, Colour	One of the 4 C's affecting diamond quality and price. Colourless gets promoted as the best, but only because other attractive colours are extremely rare.
Colorimeter	A proprietary machine for grading diamond colour.
Color, Colour Enhanced, Enhancement	The improvement of a diamond's colour by irradiation, HPHT (High Pressure, High Temperature), or coating (undesirable).
Coloured	Fancy coloured diamonds are rare, attractive and valuable.
Colourless, Colorless	What most people describe as white. Promoted as being the best "colour", mainly because real colours are so rare that there is little point promoting them.
Collection	A term used by De Beers when sorting rough, indicating higher quality and value stones.
Collet, Collets	A collet is a collar or bezel used as a diamond setting.
Commercial	Used meaning medium to low quality as opposed to fine gem quality. Cheap.
Commercial White	A dealers term for "off-white".
Commodity	Industrial diamonds are an important commodity, gem quality diamonds are not sufficiently homogenous to be classed or used as a commodity.
Compactness	Diamonds provide a highly compact store of wealth or value, which makes them easy to conceal, transport, store, or smuggle.
Comparison	Comparison of diamonds can be quite difficult for the amateur or consumer, but it can be important to ensure you get the quality you expect. Even laboratories perform much of their grading by comparing one stone with a stone of known quality.
Condé Pink	An historic 9.01 carat pink diamond given to Louis de Bourbon in 1643 by King Louis XIII of France, and now in the Bourbon family museum in the Chateau de Chantilly
Congo	The Republic of the Congo is another important source of diamonds, which are its main export, but years of conflict have weakened its economy. Probably still the 4th largest producer by value.
Conflict	Much publicised aspect of diamond exploitation.
Consolidated	De Beers Consolidated Mines (DBCM or D.B.C.M.). Formed in 1888, by Cecil Rhodes merging his own holdings with those of Barney Barnato.
Conspiracy, Conspiracies	There was a conspiracy to steal the diamonds from the Millennium Dome exhibition, including the Millennium Diamond. De Beers have also been believed to have been party to numerous conspiracies to retain control of its diamond monopoly during its long history.
Consumer Confidence Programme	A De Beers initiative to promote "disclosure", and provide training and advice for diamond professionals including retailers.
Crap	Famous description by Gerald Ratner of some of his products, causing the share price of Ratner's to collapse. Ratner and / or Ratners is a trade mark of Signet Group PLC, owner of H. Samuel, Ernest Jones, and others.
Crater of	Arkansas's diamond site, the Crater of Diamonds State Park, is the eighth largest diamond-bearing deposit in the world. Located in southwest Arkansas, this is the world's only diamond-bearing site open to the public, to prospect for real diamonds.
Created	A description of synthetic diamonds as opposed to natural ones.
Critical Angle	The angle of incidence of light measured from the normal (90%) beyond which Total Internal Reflection will occur. From diamond to air, this is a very low figure of 24.4°.
Crown	The top part of a diamond, above the girdle.
Crown Angle	The angle between the girdle and the crown of a diamond (taken as the kite facets).
Crown Height	The height or depth of the top part of a diamond, above the girdle.
Crown Jewels	Collection of diamonds, other gemstones, jewellery and regalia, belonging, usually to the British Royal Family, although the term could apply to the equivalent collections of other countries.
Crystal	A diamond is a large single crystal of carbon.
Crystal Structure	Diamonds normally crystalise with a cubic structure, as a face centred cube (FCC or F.C.C.), but can crystalise with a hexagonal structure.
CSO, C.S.O., Central Selling Organisation	Part of the De Beers group of companies.
Cube, Cubes	A cube is a rough diamond with approximately cubic shape.
Cubic	Diamonds crystallise in the cubic system.
Cubic Zirconia	Cubic Zirconia, CZ, or C.Z., is the most successful diamond simulant. Chemical formula ZrO2.
Culet	The point or small facet on the bottom of most round or brilliant cut diamonds, as opposed to a keel on other cuts.
Cullinan, Cullinan I, Cullinan II	The Cullinan was the largest rough diamond ever found (at 3,106 cts), and the Cullinan I was until recently the largest polished diamond (530 cts). It forms part of the British Crown Jewels.
Cultured	A word used to describe synthetic diamonds, in parallel with cultured pearls.
Cushion	A shape of diamond, four sided with curved sides, rather like an old television screen.
Cut	One of the four C's of diamond quality. Also a portion of a diamond parcel split at a random point rather than by selection. Used when a buyer wishes to buy a smaller parcel than is being offered by the seller.
Cuts Glass	That fact that diamond will cut glass is often cited, by the less knowledgeable, as some kind of proof that something is diamond. A claim often made by snake oil salesmen and other charlatans selling imitations and attempting to impress potential mugs punters customers.
Cutter	One who cuts or polished diamonds.
Cutting	The process of cutting, grinding, or polishing rough diamonds into finished goods.
CVD	Synthetic diamond can be made by the CVD (Chemical Vapour Deposition) process.
CZ, C.Z.	Cubic zirconia, the best simulant yet produced, although there are arguments in favour of moissanite. Chemical formula ZrO2.

There are currently over 600 entries in this table.
Over 90 of them have page links to a page on this site. Eventually, we intend to add a more complete description for most entries, each on its own page. Please watch this space!