Our Glossary
Take a deep dive and learn some of the key terms to describe a diamond.
Abrasion – A small scratch on a diamond’s surface.
Appraisal - A written estimate of the approximate retail replacement value of the item described. They can be used for insurance purposes and should be updated every few years.
Asscher Cut – A fancy shaped diamond with a squared shape and prominently cut corners. They have straight, step-like facets similar to those exhibited by emerald cut diamonds.
Baguette – A baguette is a rectangular-shape cut of diamond
Bearded Girdle – A girdle that exhibits a number of tiny, hair-like fractures that extend into the diamond
Bezel Set – In a bezel setting, the diamond or other stone is secured to its mounting via a thin strip of metal rather than prongs.
Blemish – Blemishes are often seen on diamond surfaces. These external characteristics include abrasions, nicks, extra facets, polish marks, naturals, and scratches. Many are not visible to the naked or untrained eye.
Brilliance – The intensity of the white light perceived by the eye when viewing a diamond’s crown, including from external and internal reflections. Clarity, polish, proportions, symmetry, and the quality of workmanship are factors that contribute to a diamond’s brilliance.
Brilliant Cut – A round-cut diamond that features triangular and kite-shaped facets that extend from the stone’s centre to the girdle edges of its crown and pavilion.
Bruise – An imperfection that breaks a diamond’s surface. Usually the result of the diamond hitting a hard surface.
Canary Diamonds A canary diamond is a common term used to describe a yellow diamond. GIA uses terms, such as fancy light yellow, fancy yellow, fancy intense yellow and fancy vivid yellow, among others to identify canary diamonds.
Carat – One carat equals 0.2 grams (200 milligrams). This is a measure of weight rather than size. It should not be confused with karat (the measure of the purity of gold).
Cavity – A tiny opening that breaks a diamond’s surface.
Channel Set – A setting style that features two parallel walls that hold diamonds and other stones in place, with no metal between the stones.
Chip – A jagged, shallow break that affects value and poses a potential durability problem.
Clarity – A rating that affects price and beauty, and that describes the relative absence of blemishes and/or inclusions in a diamond
Cleavage – A breakable weak point or fracture, usually caused by weak molecular structure. A cleavage is likely to split if struck in a certain direction, and in uncut diamonds, it is used as a natural site for splitting crystals prior to cutting and polishing.
Cloud – An inclusion that can make a diamond appear hazy or even milky in appearance when viewed under magnification. Most clouds cannot be seen with the naked eye.
Colour – A diamond’s tint. Colour is determined by comparing each diamond to a set of authenticated master diamonds scaled from colourless (D) to saturated (Z).
Colour Origin – The basis of a coloured diamond’s hue, including natural, enhanced, high temperature, and high pressure treated.
Conflict Diamond - A diamond (also known as a blood diamond) mined to fund violent conflict and/or civil war against a legitimate government. Such mining is, typically, also linked to dire human rights abuses. Blood diamonds have originated in Africa: Angola, the Central African Republic, Côte d’Ivoire, the Democratic Republic of the Congo (DRC), Liberia, the Republic of Congo, and Sierra Leone. It should be noted, that the amount of conflict diamonds as a percentage of world diamond production has fallen dramatically, currently resting at about 4 percent. In countries where legislation is in place prohibiting the sale of conflict diamonds, the percentages are much lower.
Crown – The angled edge of a diamond or other gemstone, located between the girdle plane and table (top).
Cubic Zirconia (CZ) - The most imitation diamond simulant on the market today. This is a cheap imitation and NOT a laboratory grown diamond. Laboratory Grown Diamonds are 100% and NOT diamond simulants such as CZ.
Culet – A diamond’s bottom facet, located at its tip. Not all diamonds have culets.
Cushion-Cut – A brilliant-cut rectangular or squared diamond shape with curved sides, and rounded corners.
Cut – A diamond’s surface features precisely proportioned facets that largely determine its beauty by emphasizing dispersion, brilliance, and scintillation, or by maximizing its size.
Chemical Vapor Deposition (CVD) technology – This is one of the technologies used to enable crystallisation of carbon over a diamond substrate. In the CVD process, methane gas is activated using microwave energy to a temperature approximately to 2000-3000 F causing it to break and release carbon atoms, depositing onto a diamond substrate. This slowly grows layer by layer, atom by atom. It is a natural process of cystal growth resulting in similar kinds of inclusions and defects that occur in mined diamonds and is beyond human control once the process starts. In terms of technical performance, the CVD technology considered to be the most sophisticated method of Laboratory Grown Diamond production. Hence, all Chelsea Rocks diamonds are created using the CVD method.
Depth – A diamond’s height, measured in millimetres from its point or culet to its table.
Diamond – A diamond is a mineral that has crystalized in the cubic system and ranks 10 on the Mohs scale of hardness. Diamonds are divided into two main categories: Type I and Type II.
Dispersion – Also known as “fire,” dispersion refers to the separation of white light into different colours.
Double prong: A Double Prong is when two prongs of the same size and shape are created side-by-side to hold the stone in place. This style of prong setting is purely decorative and also adds security.
Durability – A diamond’s ability to resist wear, based on its toughness, stability, and hardness.
Emerald Cut – A square or rectangular cut of diamond with diagonal corners. Not to be confused with Emerald gemstones!
Estate - A piece of jewellery that is being sold as 2nd hand.
Eternity - This is when a ring’s side stones extend all the way around the band without any plain metal showing.
Eye Clean – A term that indicates that a diamond has no flaws that are visible to the naked eye when viewed face up, 12 inches from the viewer.
Facet – Any flat, polished surface on a diamond or other gemstone.
Fancy – Shapes other than single cut or round brilliant cut are considered to be “fancy.” Hearts, ovals, pears, and marquise shapes are examples.
Fancy Colours – Most diamonds are colourless. Fancy coloured diamonds are typically light pastel colours such as pale pink, blue or Canary yellow. Since recently these rare and expensive diamonds have been out of reach for most people but can now be produced in a laboratory.
Fancy Cut – Although the round cut is the most popular shape for diamonds and some gemstones and is on the more expensive side compared to other shapes, all shapes other than round are considered Fancy Cuts.
Feather – A small fracture inside a diamond, sometimes extending to its surface and sometimes completely enclosed.
Fingerprint – Any unique identifying characteristic on a diamond
Finish - Symmetry and Polish are together considered as finish characteristics and are indicative of the care and craftsmanship of the cutter.
Fire – Flashes of spectral colour that reflect from a diamond’s interior when it is moved while being exposed to light.
Flaw – Any internal or external imperfection; most diamonds have flaws.
FL (Flawless) Grade – This is the ultimate clarity grade, meaning it is void of any imperfections. Very few stones receive this grade and those that do are priced accordingly.
Fluorescence – Certain diamonds exhibit coloured luminescence (usually blue) when exposed to strong sunlight or ultraviolet light.
Fracture Filling – Fracture filling is a type of treatment a stone can receive in order to enhance it. Fractures are synthetically filled thus perfecting the stone.
Four Cs – Also known as the 4Cs, these features include cut, colour, clarity, and carat weight. They are used to evaluate and compare diamonds.
GIA – Gemmological Institute of America
Girdle – A girdle is the narrow band encompassing a polished or faceted diamond or gemstone. It essentially separates the crown (upper section of a polished stone) from the pavilion (the lower section).
Grading report -
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.
Graining – Lines that show the crystal structure’s growth pattern. Sometimes visible on a diamond’s external surface, and sometimes visible internally.
Hardness – A diamond’s ability to resist scratches
Heart Cut – A brilliant cut diamond with a heart shape; pointed at one end with two rounded edges separated by a “V” shape at the other.
Hearts & Arrows - Patterning achieved in a round diamond through a high degree of facet precision. The level of optical precision can be assessed with a special viewer that reveals 8 hearts from pavilion view and eight arrows from table view. Often abbreviated to H&A
High Pressure and High Temperature (HPHT) – HPHT is one of technologies used to grow Laboratory Grown Diamonds and is considered less sophisticated than the CVD production method, favoured by Chelsea Rocks. In the HPHT process, a diamond seed (real diamond) is placed along with graphite and a metallic catalyst covered with a ceramic shell in growth chamber. As the pressure and temperature increase to about 55 K Bar and 1500 C, respectively the carbon atoms are released from the graphite through the molten catalyst and the atomic process of crystal growth starts on the diamond seed. The diamond grows layer by layer and atom by atom over a period of 8-10 days.The new diamond is cleaned and ready to be cut and polished, just like any other rough diamond extracted from below earth.
I (Included) Grade - This is the lowest clarity grade. Stones with this grade have inclusions that are visible to the eye.
IGI - International Gemmological Institute. A laboratory which offers a grading report. IGI also produces written appraisals.
Inscription - Laser inscribed numbers and/or letters, usually corresponding to a lab report number.
IF (Internally Flawless) Grade – This is one of the highest clarity grades.
Inclusion – A catch-all phrase describing imperfections and other internal flaws. Most diamonds have inclusions. This can be a cavity, a crystal, a feather, internal graining, pinpoint, and so forth.
Kimberly Process - The Kimberley Process (KP) is a joint governments, industry and civil society initiative to stem the flow of conflict diamonds. The Kimberley Process Certification Scheme (KPCS) imposes extensive requirements on its members to enable them to certify shipments of rough diamonds as ‘conflict-free’.
Knot – A type of inclusion in which one diamond crystal is lodged inside a larger diamond crystal.
Laboratory Grown Diamond - A laboratory grown diamond is 100% diamond and possesses the same chemical composition, optical and crystal structure as a mined diamond. A LGD should not be confused with diamond simulants such as Cubic Zirconia or Moissanite, which have different optical and physical characteristics and are NOT diamonds.
Lab Report - An identification and quality analysis report from a gemmological lab, often referred to as a certificate
Leakage – This is when the light that enters the stone fails to reflect back through the crown and is instead dispersed through the pavilion part of the diamond.
Loose Diamonds- Not mounted. Usually stored in a parcel paper.
Loupe - A diamond loupe is a special lens used to magnify 10x what the human eye is able to see.
Louping - A term used when on inspects a diamond through a gemmologist magnifying glass – known as a loupe.
Marquise Cut – A brilliant cut diamond shape that features two curved sides and tapered, pointed ends. Most marquise diamonds are brilliant cut.
Melee – A group of gemstones including diamonds, usually used to accent a larger stone and typically weighing .12 carats or less.
Moissanite – Synthetic moissanite is a modern diamond simulant with good hardness and dispersion. It can fool the simple thermal conductivity probes used to easily detect Cubic Zirconia and most other simulants. However, it is doubly refractive, allowing it to be identified with the trained eye. Moissanite is a DIAMOND SIMULANT and NOT to be confused with a laboratory grown diamond, which is 100% diamond.
Mounting – The mounting is the part of a setting in which a stone is set.
Naked Eye - Inspecting a stone with one's eye as opposed to using some sort of a loupe.
Needle – A thin, rod-shaped inclusion found within the diamond. It is one of many possible inclusions.
Nick – A nick is a minor chip, a surface break.
Opaque – A characteristic of a diamond or coloured gemstone that makes it neither transparent nor translucent. This means it does not transmit light.
Oval Cut – A brilliant cut diamond shape with curved sides and rounded ends.
Pavé – A jewellery technique involving small diamonds set very close to one another forming a solid field of diamonds, like a road paved with stones. Micro pavé is typically done by a jeweller working under a microscope.
Pavilion – The faceted, steeply angled bottom portion of a diamond that typically sits below the mounting. It is located just below the girdle.
Pear Shape – A teardrop cut diamond with one wide, rounded end and one pointed end. This is one of the fancy cuts for diamonds.
Pink - A very rare natural fancy colour. Radiation treated diamonds (not natural) can also create a pink colour variation.
Pit – A pit is a minuscule indentation that can appear on the surface of a diamond.
Piqu’e – This is another term used to describe an inclusion which will affect the clarity grade of a stone.
Point – A weight measurement equal to 1/100 carat. For example, A 0.50-carat diamond is equivalent to 50 points.
Price Per Carat - One of the main considerations used determine the price of a diamond is the carat weight. However, please note that since stones are more difficult to come by, the price isn't simply doubled as the carat weight increases. Hence, a two-carat diamond is not two times the price of a one carat stone, and a six-carat diamond is definitely not double the price of a three-carat stone. Therefore, people will often ask or quote the price per carat of any specific stone, taking into account additional technical parameters.
Plotting Diagram – a schematic that approximates the shape and style of a diamond while also noting its internal and external characteristics.
Princess Cut – A brilliant cut diamond shaped like a square or rectangle, with pointed corners.
Proportions - Proportions refer to the relationship between the various measurements of a diamond. The size of the table compared to the girdle, pavilion, crown, depth, and culet of the diamond.
Radiance – The amount of light refracted and reflected by a diamond, also referred to as “life” or “sparkle.”
Rose Cut: A stone cut with a flat base, with the upper facets cut to a point. Normally encountered in antique jewellery starting with the 17th century, but making a comeback in the last few years.
Radiance – The amount of light refracted and reflected by a diamond, also referred to as “life” or “sparkle.”
Rose Cut: A stone cut with a flat base, with the upper facets cut to a point. Normally encountered in antique jewellery starting with the 17th century, but making a comeback in the last few years.
Rough Diamond – An uncut, unpolished diamond.
Round Brilliant Cut – A traditional round diamond, usually with 57 or 58 facets. This is the most popular colourless diamond shape.
Round Brilliant Cut – A traditional round diamond, usually with 57 or 58 facets. This is the most popular colourless diamond shape.
Saturation – The level at which colour is seen.
Scintillation – The mirrorlike reflections a diamond’s facets make when it is turned while being exposed to light.
Stacking ring or stacked set - This refers to the stacking of multiple bands or rings together
Synthetic: Man-made products which are designed to imitate diamonds. Examples include Moissanite or Cubic Zirconia (CZ). Laboratory Grown Diamonds are NOT synthetic or diamond simulants, they are 100% diamond as they are 100% carbon. Synthetic products do not contain any carbon properties.
Solitaire – Jewellery containing just one diamond, i.e. a solitaire engagement ring.
Symmetry – A diamond’s overall uniformity, which ranges from poor to ideal.
Table – As the name suggests, the table is the top, flat horizonal facet on the uppermost surface of a cut diamond.
Tone – Tone refers to how light or dark a colour may appear
Toughness – Durability - the diamond’s ability to resist breakage.
Transparency – The refers to the amount of light which at is transmitted through a diamond.
Treatment - Various chemical processes and materials used to enhance a diamond’s appearance.
Triple Ex - When the symmetry, polish and cut of a diamond are all graded as an 'excellent cut.'
Twinning Wisp – An irregular, ribbon-like inclusion inside a diamond
VS (Very Slightly Included) Grade – The VS clarity grade is one of the more common grades of diamonds that the general public acquires.
VVS (Very Very Slightly Included) Grade – The VVS clarity grade is one level between IF and VS. Inclusions within a stone graded with a VVS clarity usually cannot be determined without a microscope.
Wedding Set: The pairing of an engagement ring and wedding band
Wesselton: Originally the name of a diamond mine producing white diamonds. Nowadays a less used reference for the colour of a diamond. Wesselton is H coloured. Top Wesselton refers to colours F and G, and some may also call F a Top Wesselton+.
White Gold – one of the most commonly used metals for diamond ring settings. White gold is not a stand-alone metal. It is an alloy of gold and nickel or palladium. The lustrous reflective white surface is a result of rhodium plating.
Wisp – A thin, curved inclusion that can appear as a hair or cloud shape on a diamond
X-Ray Fluorescence – A diamond’s ability to emit secondary x-rays when it is exposed to an x-ray. This characteristic is used to identify a diamond or other stone by indicating its chemical elements.
Yellow Gold - While pure gold is yellow in colour, coloured gold can be developed into various colours. These colours are generally obtained by alloying gold with other elements in various proportions.
Z Colour Diamonds - Z colour is, strong yellow colour and the colour-grade before a diamond is graded as Fancy Light Yellow with GIA. O-P to Y-Z colour is often mistaken for Fancy Yellow.