Basic Terminology

Now that you know a little more about the history of diamonds and their current market, and you’ve decided that you want to invest, you’ll need to do some research on a few important matters.


At CEDEX, we’ve gone ahead and grouped together a list of terms we think you simply MUST know if you want to succeed in the diamond world. Some of these terms are more basic; others, slightly more advanced, but all are great to know as you aim for success on the CEDEX platform and elsewhere.


Just like with our glossary page – this page too will sometimes be updated with more terms, so if you would like to suggest a few you feel are missing – let us know!


The 4 C’s: All diamonds share certain features that allow us to compare and evaluate them; these features are called the 4Cs: carat weight, clarity, colour and cut.


APPRAISAL: Official valuation made by a certified gemologist, which gives an estimation of the value of an item, typically used for insurance purposes.


ALLUVIAL MINING: Mining for diamonds that have been carried by wind and water down rivers, over millions of years.


BOART: A very low-quality diamond usually used for industrial purposes.


BRUISE: A crumbling surface on a stone.


BRUTING: The shaping of the girdle by rotating one diamond against another.


CANARY DIAMONDS: A common term describing a yellow diamond – see Yellow Diamonds.


CERTIFICATE: Some laboratories refer to ‘grading reports’ as certificates.


CERTIFICATION: A document issued by an independent gemmological laboratory that details the vital characteristics of a diamond.


CLIVAGE: A term normally applied to the cheaper qualities of rough diamonds, which need to be split before being processed further.


DIAMOND GAUGE: Also known as a “leverage gauge,” this instrument measures a diamond’s proportions to a 100th of a millimetre.


DIAMOND PIPELINE: The industry value chain that runs from consumers and retail stores to jewellery manufacturers, cutters and polishers, back to producers and explorers.

GRAINERS: Normally refers to smaller stones, whose weight is expressed in grains rather than in carats (particularly rough stones weighing less than 2.79 carats and polished stones weighing less than 1 carat).


HEARTS AND ARROWS: Ideally-cut symmetrical diamonds will exude arrows when viewed “face up” and hearts when viewed “face down;” can be seen with certainty only under a special microscope.


ICE: Diamonds are not only called ‘ICE’ due to their clear, colourless crystal appearance, but because of their ability to conduct heat higher than any other gemstone. Diamonds can pull heat away from any warm object they encounter. You can test this by pressing a diamond against your lips or skin – it will give you a cold and icy feeling.


IMPERFECT: The diamond imperfection grade at the low end of the ‘flawless-to-imperfect’ scale. An imperfect diamond contains any external blemish or internal inclusion or flaw that are visible to the unaided eye, or that have a serious effect on the stone’s durability.


KIMBERLEY PROCESS (KP): An intergovernmental rough diamond certification scheme aimed at preventing conflict diamonds from entering the legitimate diamond value chain.


KNOT: A diamond crystal within another diamond crystal. Such inclusions are considered flaws and often cause a problem with the overall polish of the diamond. They cannot be easily removed.


LASER INSCRIPTION: Laboratories inscribe the grading report or certificate number on a diamond’s girdle.


MELÉE: A term used to describe small cut and polished diamonds. The diamond weight for melée diamonds ranges from as low as 0.001 carats (1,000th/carat) to 0.18 carats.


SMALLS: Colloquial term for rough diamonds, valued at under three grainers. A grainer is a unit often used in the diamond trade to approximate the weight of a rough diamond; a grain is about 0.25 carats.


SETTING: The entire metal mounting holding the polished diamond or diamonds. The design and workmanship of the setting is critical to the overall beauty of a diamond ring. Synonymous with “mounting.”


YELLOW DIAMONDS: Generally, most diamonds contain nitrogen which gives them a slight yellow tinge; however, diamonds with more intense yellow hue are considered (canary) fancy coloured diamonds, which make them rare and more valuable.