Glossary

A

Abraded Culet

The sharp finish at the lowest point of a diamond can be damaged by use. This is a defect in the polishing quality and under certain can affect the class evaluation.

Abraded Facet Edge

Due to the fact that diamonds are highly hard stones they tend to create very sharp edges during the cutting and polishing procedure. Also, their edges tend to get damaged after years of use if not handled with care. Worn edges tend to degrade the quality of shine and reduce the final value.

Abrasion (wear / corrosion)

Abrasion is the surface wear of a polished diamond. Generally describes any abrasions, scratches and corrosion that appear on the surface of a diamond. This wear is affecting the quality of polishing and must be mentioned in the certificates.

Adamas (Diamond)

Adamas in Greek means someone or something that can be tamed. The term was originally used for extremely hard materials. Now it is exclusively used for the hardest of all metarials: diamond.

Annealing (increase in temperature)

We tend to improve or change the color of a diamond with annealing. Radiation can also increase the temperature of a diamond.

Appraisal (evaluation)

A written statement that mentions the retail value of a diamond or of a jewelry. This evaluation is not considered as a certificate.

Asscher Cut

A kind of cut with square cut corners. The edges of the diamond run parallel in steps. Asscher cut resembles emerald-cut but the shape of the diamond is square instead of rectangular.

B

Baguette Cut

Type of rectangular cut with sharp corners and elongated edges which run parallel to the girdle.

Bearding

The term bearding refers to the tiny, hairline cracks along the girdle. It is caused during the cutting and polishing process and has an impact on brilliance and purity.

Bezel Facets

The main facets of the crown in round brilliant cut.

Blemish

Blemish is any defect on the outer surface of a polished diamond. It may be a crack or a scratch or abrasion, or pothole etc. These flaws are always mentioned in the certificates.

Blood Diamonds

Diamonds that come from areas that are controlled by rebel and dissident forces, which act against the interests of the legitimate government. The money from selling blood diamonds is used for weapons, terrorist acts etc. Attempts are made by the global diamond centers to stop trading diamonds that come from these areas.

Bow Tie

Bow Tie is a shadow formed along the center of fancy-cut diamonds. This indicates that the diamonds are of poor cut quality.

Briefca

A special paper used as protection of diamonds during transportation.

Brilliance

Determines the intensity of light reflected from the diamond’s surface. Brilliance is the most important property of a diamond.

Brilliant cut

A kind of cut with triangular and rhombic facets. Round brilliant cut is the most common kind of cut for diamonds with 32 facets plus a large round table. The facets at the bottom are only 24 and end as a cone. The round brilliant cut diamonds may be oval, heart-shaped or pear-shaped, radial, marquise etc.

Briolette Diamond

A kind of cut that gives diamonds the shape of a tear drop.

Bruted Girdle

The girdle in diamonds can be polished, unpolished or polished at the edges. If the girdle is unpolished, it is called Bruted.

Burn Mark

mperfection on the surface of polished diamonds that looks like ice or like an area with spilled oil. When the diamond is hastily polished, the heat tends to leave marks on the surface. The burn marks tend to reduce the polish quality and must be mentioned in the certificates.

C

Calf’s Head Diamond

A kind of triangular cut with cut edges that shape the diamond as the head of a calf.

Canary Diamond

Term used to describe fancy yellow diamonds.

Cape Series Diamonds

A classification for color diamonds. It starts with the almost colorless diamonds and gradually progresses to the slight yellow ones, the light yellow ones and the visibly yellow diamonds. When a diamond is vividly colored, is classified as fancy. The Cape Series classification is used for diamonds for other colors too.

Carat

Unit of weight used for precious stones and is equivalent to 1/5 of a gram. 

Carbon

Carbon is the only element of the chemical composition of the diamond (C).

Carbon Spots

Tiny dark graphite inclusions

Cavity

A void or opening in the surface of a diamond

Certificate

Document that fully and accurately describes the characteristics of a diamond. Only authorized and independent laboratories can issue such written reports

Chameleon-Type Diamond

Very rare diamonds with color that is not stable. Their color depends on the type of light used (solar, artificial room light, etc.) and the ambient temperature.

Champagne Diamond

Diamonds in the color of champagne (light brown yellow color).

Chip

When diamonds come into contact with a sharp object, a chip of them may break off that will affect their brilliance and clarity.

CIBJO (World Confederation of jewelers)

This is the international confederation of national trade organizations jewelers. The purpose of CIBJO is to encourage, harmonize and promote international cooperation in the jewelry industry and examine issues of concern for the international trade.

Clarity

Clarity is one of the four evaluation factors of diamonds (4Cs). In the Greek market clarity is translated as purity. During the crystallization the crystal encloses foreign matter from the environment. These inclusions may spoil purity. That is why the purity of inclusions gives value and uniqueness in a diamond.

Clarity Enhancement

A set of specialized procedures that improve the appearance of diamonds, making them more clear. These advanced techniques get rid of any black inclusions (laser drilling) and fill voids and fractures (fracture filling) in diamonds.

Cleavage

Some crystals exhibit a very rare vector quality. The crystals break always in defined levels which are parallel to each other. For example, a diamond breaks at levels that are parallel to the faces of the octahedron.

Closed Table

Commercial term used for diamonds that have a small table facet compared to their size

Cloudy inclusions

Typical inclusions usually consist of numerous tiny inclusions that are concentrated in a very small area and give the impression of smog.

Coated Diamonds

Type of curing used in older times. This technique applies a kind of paint on the surface of the diamond and covers some defects and / or improves the color and brilliance of the diamond.

Cognac

The commercial term of dark brown colored diamonds.

Conflict Diamonds

Diamonds that originate from areas that are controlled by rebel and dissident forces, which have conflicting interests with the legitimate government. Rebels use money from these diamonds for weapons, terrorist acts etc.

Crown

Is the upper portion of a diamond, ie the part located above the zone.

Crown Angle

The angle between crown and girdle in diamonds. Brightness and light diffusion depend on the crown angle.

Cubic Zirconia

The cubic zirconium is a technical isotropic crystal. In other words, a laboratory created colorless diamond.

Culet

The lowest point of the pavilion in a diamond. The finish may either be sharp, or vertex or a tiny pavillion.

Cushion Cut

Type of cut with a mainly rectangular shape with rounded corners.

Cut and Cut Grade

A quality assessment of the diamond’s cut that is always mentioned in the certificates.

Cut-for-Weight

Term that refers to diamonds that are cut in such a way as to have the smallest possible weight loss from the original stone. 

D

Deep Cut

The term "Deep Cut" states how the ratios in the dimensions of polished diamonds are shaped. If these rations are not the correct ones, then diamonds are not fully reflecting the light and loose in brightness and color. Needless to say, the value of this diamonds is not the ideal.

Depth

The length of a diamond in millimeters or in%, measured from the table facet to the bottom of the culet. The term is also known as 'total depth' or 'total height'.

Depth Percentage (height ratio)

The overall height compared to the diameter of the round brilliant cut diamond.

Diameter

This is the diameter of the round brilliant cut. This diameter acts as a yardstick when we shape a diamond as a brilliant. All dimensions (height, depth etc.) are given as percentages related to the diameter of a diamond.

Diamond

Diamond is the crystalline form of mineral carbon. Diamonds are the hardest mineral that man known so far. Actually, they are rare crystals found in rocks and only with the help of specialized cutting and polishing process we can bring out their true beauty.

Diamond Bourse

It is an organization founded by members of the global diamond industry. Its main purpose is to create the international rules for a smooth commercial trade of diamonds. The diamond bourse has established a legal and ethical framework for its members in order to ensure the confidence of their consumers. Another term for the Diamond Bourse is "Diamond Club".

Diamond Dust

Microscopic diamond particles that are commonly used in high quality abrasive and polishing tools either for diamond polishing or in the industry (grinding, cutting etc).

Diamond Gauge

Instrument used for measuring the size of a diamond.

Diamond Grading Reports

Reports conducted by qualified and specialized gemological centers for a fee. The certificate of authenticity and categorization of a diamond gives you the real value of your diamond.

Directional Hardness

Directional hardness is the unique property diamonds have and measures their hardness, (which is not stable across its dimensions). I.e. in some directions diamonds seem to be harder than in others. This property allows us to choose the exact spot where we will cut a diamond.

Dispersion

Dispersion is the ability of a material to analyze the light into its component colors. Rainbow colors are a very common example of this.

Durability

Durability is a term used to show how resistant is a material to everyday wear. The resistance is determined by two main factors, the hardness (abrasion resistance) and consistency (resistance to breakage). 

E

Eight Cut

Old kind of cut that has only sixteen facets plus one at the crown. In other words, the crown has eight facets and the pavilion another eight. This kind of cut is today commonly known as «single cut».

Emerald cut

This is a kind of rectangular or square cut with large facets, which reveal the color of the precious stones.

Equivalent Colour Grade (ECG)

Some colorless diamonds or some diamonds that belong to Cape Series have a brown or gray tint, which is not visible when the stone is observed from above. These diamonds have less value that the ones that actually have no tint.

Extra Facet

An additional facet not provided in the original cut plan is called extra facet. We use an extra facet in order to erase any flaws or defects in the raw stone, without losing carats. These additional facets must me mentioned in the certificates.

Eye-Clean

Term used for expressing the clarity of the stone. That is, the stone has no inclusions seen by naked eye and we need a magnifier in order to see if there is something inside.

Eye-Visible

Term used to express the clarity of the stone and indicates that there are inclusions which we can see with a naked eye (without the aid of a magnifier).

F
Faceted Girdle

In round brilliant-cut diamonds girdle has not a standard shape. The girdle may be polished, unpolished or polished with small flat facets.

Facets

Facets are tiny surfaces on a polished diamond that determine its final form. The way light interacts with these facets affects the flare and brilliance of a diamond.

Fancy Color

Term used for all colored diamonds with the exception of white and black colored ones.

Fancy shapes

Any diamond that is nor round-shaped is called fancy-shaped diamond – for example, marquise, square, emerald, oval, heart and pear shaped and so on.

Feather

Feather is a kind of inclusion inside a diamond. This flaw is sometimes described as a crack or break.

Finish

Term used for describing the outer part of a diamond. A well polished diamond is a good finished diamond. 

Fish Eye

Fish eye is an intruding white ring that appears under the table facet in round brilliant cuts. This is due to the incorrect reflection of light on the girdle because of a shallow pavilion.

Flare

The term "flare” is in a sense synonymous with the term "dispersion”. When light enters a diamond is analyzed into the colors of a rainbow. The proportion of these analyzed colors that are reflected in the interior of the stone and are visible to the eye is called "flare”.

Flash Effect

Color reflection phenomenon that is happening inside the diamond and is caused by the special glass filler used to fill gaps or cracks in diamonds. This special filler fills the gaps but has a different behavior in the light. This difference creates color reflections.

Flat Diamond

This is a commercial term that refers to diamonds with a small crown and/or shallow pavilion. The "fish eye” phenomenon is very usual to flat diamonds and they, also, lack in brilliance and flare.

Flawless

Term that shows how clean diamonds are. Flawless diamonds are the ones that have no inclusions.

Fluorescense

Fluorescence is the phenomenon in which when the light is cast in a solid body, tends to return back either colored or colorless. Most diamonds strongly exhibit the phenomenon of fluorescence with white, blue or yellow color. Fluorecence is always mentioned in the certificates.

Four C's

These are the four fundamental criteria by which we determine the quality and value of a diamond: cut, color, clarity and carat. We would say and the Certificate is the fifth C, because it is an official document that proves all other C’s.

Fracture

Some crystals have the tendency to break into non-planar surfaces.

Fracture Filling

Fracture filling is an enhancing procedure where gaps and fractures are filled with a special glassy resin.

G

Gem Quality

Gem quality is valuable quality. Only 20% of all diamonds mined each year can be used in jewelry. The remaining 80% goes to industrial purposes. Each diamond is transparent in color and weight, so it can be used as a valuable gemstone.

Gemology

Gemology is the science that studies the precious stones, in terms of their genesis, their authenticity, their properties, laboratory synthesis, methods to improve their appearance, etc. 

Girdle

Is the outer perimeter of the diamond between the crown and the pavilion.

Girdle Thickness

Girdle thickness measures the girdle height in millimeters. Also, it is measured as a percentage of the total diamond height. This percentage is always mentioned in the certificates as a medium, thick or thin girdle.

Grading Report

This is a report that describes with accuracy all the features and qualities of a diamond. Such evaluation reports are always issued by accredited and independent gemologist laboratories. The data can give us an idea of the value of the diamond. Furthermore, these reports are called Certificates and they do not serve as a financial evaluation or record of the diamond’s value in money, but state all data that could lead to an accurate monetary value.

Growth Lines

Growth lines are weak lines that are detected inside the diamond or in its outside surface. These lines are formed during the birth of diamonds, and show the growth of the crystal.

Gypsy setting

Gypsy setting is a kind of setting usually used in men’s jewelry. The piece forms a continuous line that becomes thicker at the top. The gem is usually placed at the top of the jewel.

H

Hardness

Hardness is the resistance a material shows to friction, i.e. to scratching and abrasion. Diamonds are the hardest material known to man with 10 on the Mohs scale. Diamonds are 75% harder than the second hardest natural gemstone known, which is ruby ​​/ sapphire. The term toughness has to do with hardness and cohesiveness. Cohesiveness is the resistance a gem shows to fracture and should not be confused with the hardness.

Heart-Cut 

A cut that shapes the diamond as a heart.

Hearts & Arrows

Hearts & Arrows are the shapes we see in a round brilliant cut or square cushion cut diamond as seen from above or below. If we see a diamond through the crown of the table facet we see (with a little imagination) the formation of eight arrows. When seen from below, from the pavilion side, the shapes look like eight hearts. These hearts and arrows shapes are not a proof that the stone is cut to the ideal proportions, but that it has the correct symmetry.

HPHT (High Pressure High Temperature) Treatment 

This is an improving laboratory method that changes the color of a diamond by the use of high temperature and high pressure. The chemistry of the crystals in some diamonds is affected by the high pressures and temperatures and this changes the final color of the crystal and improves the diamond’s color.

Hue 

Some diamonds of the Cape series (ie diamonds with a slight color), may have a hue in another color too, that is usually brown or gray. In other words, these diamonds may have a yellowish brown tint. This hue is always mentioned in the certificates. Diamonds that have a hue in another color have less value than diamonds with a clear color. 

I

Ideal Cut

The term is used for round brilliant-cut diamonds that have the correct proportions and absolute symmetry. There are many different "ideal proportions", with the most famous the Tolkowsky Cut. There are different ratios for each «ideal cut», so we must be very careful when we classify a diamond as «ideal cut».

Illusion setting

This is a more complex setting because the metal, surrounding stone, makes it appear larger that it really is. Also, of interest is the shape of the precious metal used.

Inclusions

These are foreign matter trapped inside a diamond during the crystallization process. The inclusions may be solid, liquid or gaseous, fractures or cracks within the diamond or traces of its structure. These inclusions characterize each stone in categories according to its purity and determine its final value.

Independent Laboratory

Independent Gemological laboratories are the laboratories that undertake the study of the precious stones and issue certificates that have nothing to do with any marketing and selling value. According to international standards, are only valid certificates issued by independent laboratories. 

Industrial Grade Diamond

These are laboratory made diamonds not eligible to be used as gems. Industrial diamonds usually have numerous inclusions and are not brilliant clear. But, they are very useful in applications like tools, drills, lasers, abrasives, etc. Only 20% of the natural diamonds are of high quality.

International Diamond Council

International Diamond Council is an international body established by the World Federation of Diamond Bourses (WFDB) and International Diamond Manufacturers Association (IDMA). This organization establishes international standards for the evaluation and classification of diamonds.

International Diamond Manufacturers Association

This is an international body established in order to encourage and promote the ideals of honesty and fair trade and improve the practices applied throughout the diamond industry worldwide.

Internationally Recognized Standards

These are the rules and regulations for evaluating diamonds. The rules are regulated and recognized by internationally recognized organizations. These organizations are CIBJO, LMHC, World Federation of Diamond Bourses (WFDB) and International Council of Diamonds. 

Irradiated Diamonds

Irradiated diamonds are diamonds that have been irradiated in order to improve and / or change their color. Irradiation is always applied with high temperatures in order to activate the color centers generated by the radiation.

J

K

Kimberlite

Kimberlites are diamond carrying rocks that bring diamonds from the bottom of the earth to the surface. They usually have blue color and are considered as the oldest rocks of the continents.

Knot

Knot is any crystalline inclusion that reaches the outer surface of a gem.

L

Laser Drilling

Lasers are used in diamonds as a treatment in order to remove any dark inclusions, which decrease the transparency and hence the stone’s market value. A thin laser beam creates a tiny hole in the diamond’s surface and removes the unwanted intrusion. Furthermore, the inclusion is removed either by the laser beam or with acid.

Laser Inscription

A thin laser beam is used to write or draw to the diamond’s surface an inscription. This inscription may be a private message, but usually is the code number of the certificate of the stone and is seen only under a microscope. This procedure is permanent and the inscription is removed only by re-polishing the diamond in a specialized laboratory by a specialist technician. The laser inscription is microscopic and completely invisible to the naked eye. One can only see with x10 magnification with a microscope or loupes. The laser inscription does not affect the color and clarity of diamonds.

Life

The vibrancy and beauty diamond emit, considering the quality of the splendor, its fire and brilliance. 

Loose Diamond

Loose diamond is a diamond that is not set in jewelry. When we want to evaluate a diamond, we usually take it out of the jewelry and then evaluate its color, cut and clarity.

Loupe

Handheld 10X Magnifier used for the evaluation of diamonds. The clarity of a diamond is only determined by x10 magnification.

Loupe clean

Term used to characterize a diamond that is evaluated with a magnification loop x10 and appears to be clean of inclusions. 

Lower-Girdle Facets

Large triangular facets of the pavilion that reach till the girdle of a diamond.

M

Marquise shape

Oval-cut shape with sharp and not curved edges. This shape is also called navette, which in French means small boat, because its shape resembles a boat.

Melee

Term that generally refers to all polished diamonds, which are smaller than 0.15 carats.

Milky Diamond

Cloudy or dull diamond with reduced transparency and brilliance. This "milky” appearance may be due to several factors, such as tiny inclusions thick or a strong fluorescence from solar radiation.

Mixed-cut

A mixed cut with upper girdle facets that follow a different kind of cut that the facets below the girdle. The most common type of mixed-cut is the round brilliant-cut in the crown and step-cut in the pavilion. 

Moh's Scale

Moh’s Scale measures the relative hardness of minerals and was named after the German mineralogist Friedrich Mohs who invented it in 1812. Minerals are classified from 1 to 10 according to their hardness. Each mineral is harder that the ones below it. For example, any mineral with a hardness of 7 in Moh's Scale can carve minerals with hardness of 6 to 1, but is curved by all the minerals with a hardness of 8.9, and 10. The diamond has the highest hardness of 10.

Moissanite

Moissanite is a rare natural mineral. Man first created laboratory moissanites in 1993 and then found this mineral in nature. It is one of the finest imitations of diamonds.

N

Nailhead

Nailhead is a shadow traced in round brilliant-cut diamonds when seen from the center of the large table facet. This shadow is created by a false reflection in the table. Diamonds with a nailhead shadow are less brilliant.

National Diamond Colour Master Set

A set of certified, registered and recognized diamonds that show all the gradations in color classification, from completely colorless to fancy colored diamonds. Master Stones are crafted based on these diamonds, which act as a criterion in the assessment of diamonds worldwide. 

Natural

Natural is the term used to describe what was left from the outer surface of the diamond crystal. In other words, it describes the portion of the outer surface that is removed by polishing. We find naturals in the girdle. These naturals are not harmful to the quality of the polish.

Natural Diamond

Natural diamonds are the diamonds that are created on earth by natural processes.

Needle

The term "needle” is used in gemology and diamond in order to describe an inclusion in the form of a needle or hair. Any matter that is foreign to the precious stone and is located inside the stone usually has the shape of a needle.

Nick

Nick is a kind of external damage, usually a tiny break in the girdle. Nicks affect the quality of the polish and must be mentioned in the certificates.

O

Octahedron

Crystals usually have octahedral shape and this shape occurs naturally in diamonds. This shape resembles two pyramids joined at the base.

Off-Make

Commercial term used for diamonds that have a poor quality polish and cut.

Old Mine Cut

This is an old kind of cut that has almost the shape of cushion-cut. This kind of cut has a deep pavilion, a small table compared with the current round brilliant cut, a high crown and there was a large culet.

Oval Cut

Type of cut with a perimeter in the shape of an ellipse which is dominated by triangular faces and which generally follows the philosophy of brilliant cut.

Overblue

The term refers to diamonds with a strong blue fluorescence under ultraviolet radiation (especially at long wavelengths). This term was used incorrectly in the past for diamonds with a good color quality. Colored diamonds that sometimes exhibit strong fluorescence are cloudy / milky in sunlight is or light seems to move through them (oily appearance). 

P

Pavilion

The bottom part of the gem that is below the girdle and ends up to culet.

Pavilion angle

The angle the girdle has in respect to the main facets of the pavilion.

Pavilion Depth Percentage or Pavilion Depth

The height of the cone in millimeters or %, compared to the diameter of the round brilliant cut. The height of the pavilion is of paramount importance if we need to have correct proportions in the cut, plus a gem with brilliance and flare.

Pavilion Main Facets

Facets in phombohedral shape that start from the lowest point of a round brilliant cut diamond (culet) and reach the girdle.

Pear Cut

Kind of cut with an distinguished shape of a drop or pear.

Phosphorescence

Solar or ultraviolet radiation renders a body with luminous energy. When a body continues to emit light energy, in color or not, after its exposure to light, then we say that it shows phosphorescence. All bodies tend to emit light for a short period of time. That is they illuminate in the dark.

Pinpoint

Pinpoint is a small spot which is encapsulated within the diamond. The concentration of many such inclusions is called cluster or cloud. These two appear as a hazy spot in the diamond.

Pit

If there is an imperfection in the outer surface of a diamond, this imperfection is called “pit”. Pits have an adversely affect in the polish quality of a diamond. 

Pitted Facet

Facets that have numerous pits.

Plotting Diagram or "Plot"

A schematic representation of a diamond, which accurately describes its size, positions and type of inclusions, plus all imperfections on its outer surface is called plotting diagram. Such diagrams with the main characteristics of diamonds serve as their ID and help us to distinguish them.

Point

Point is the hundredth of a carat. That is, a diamond weighing 0.30 carats is reported as a 30 points gem. 

Polish

Polish shows how careful and experienced is the skilled craftsman that will undertake to give shape and form to a rough diamond and transform it into a perfectly polished diamond.

Polish Grade

Polish grade is the qualitative assessment of the overall condition of the exterior surface of a diamond. The quality of polish depends solely on the experience and the skills of the jeweler and plays major part in the brilliance and flare of the stone. 

Polish Lines

Any marks left on the surface of diamond during the polishing procedure and are visible only under magnification. These marks or polish lines usually disappear during the last stage of polish. If the finished stone shows such marks under x10 magnification then these marks must be mentioned in the Certificates.

Polished Girdle

The girdle in the round brilliant cut diamonds may be unpolished, polished or polished with small facets.

Poor Cut

Cut is the procedure that shapes a rough diamond to turn into a perfect polished one. A diamond with a poor cut may be either too shallow or too deep. In this case a poor cut can affect the brilliance and the value of the diamond.

Princess Cut

Another kind of cut with square or rectangular shape and which combines features of the brilliant and step cut.

Prong or claw setting

This is a kind of setting with 4 or 6 nips that hold a diamond in place in a jewel. This setting permits the maximum amount of light to enter the stone from all angles and sometimes makes a diamond look bigger and brighter than it is. Also, this type of setting is the most secure for larger diamonds.

Proportion

The proportions or ratios of a diamond are one of the most important qualities because we want the maximum flare and brilliance. Proportions show the relation between the angles of the facets at the top and the pavilion in relation to the perimeter of the girdle.

Proportions and Proportion Grade

The round brilliant cut has certain proportions that bring out the maximum beauty of the diamond (brilliance, flare, light scatter). These proportions are in direct relation with the diameter of the total height and the individual facet heights in the crown and the pavilion. If we need a quality cut, then we must be careful with the proportions we are using, because each stone has its own unique shape that requires its own unique proportions. 

Q

R

Radiant Cut

Radiant cut is another kind of cut with square or rectangular edges (princess cut), but with corners that create facets.

Rapaport Diamond Report

Rapaport Diamond Report is the primary source of diamond pricing and market information for the diamond industry. It is an international standard that establishes the market prices of all diamond cutting and distribution centers. It is, in other words, the wholesale diamond price list used by traders worldwide in order to be a harmony in the prices.

Rough Diamond

All diamonds, regardless their shape, are called rough if uncut and unpolished. Rough diamonds, in other words, are either called rough crystals or rounded pebbles.

Round Brilliant Cut

This kind of cut is extremely popular and commercial. The diamond is round in shape with the bottom ending in a conical shape called the pavilion. This type of cut is standardized with a total of 57 or 58 facets.

S

Saturation

Saturation is the term used for the intensity and color quality a diamond shows. 

Scintillation

When a diamond reflects light, this glow is called scintillation.

Shallow Cut

The term cut refers to the angles and proportions a skilled craftsman creates in a rough diamond and turns it into a perfectly polished one. When a diamond has a shallow cut it loses flare and light cannot be dispersed through its sides and bottom part.

Shape

Shape is the form a diamond has after cutting. This shape can be round, triangular, square, marquise, pear, oval or heart.

Simulant

The imitation is any stone that is used instead of the precious stone in jewelry. Imitations look externally like the real stones and often have similar physical properties. Imitations or stimulants are used in the place of another precious stone, no matter if it is natural or synthetic. The most common imitation of a diamond is the cubic zirconia (CZ), the moissanitis etc.

Single-Cut

This is an old kind of with only sixteen facets plus a table at the top. The crown has 8 facets, plus another 8 facets are in the pavilion. This kind of cut is used today only for very small stones. The cut is also known as «eight cut».

Star Facets

Star facets are the triangular facets in a round brilliant cut diamond, which surround the table facet.

Step-Cut

Another kind of cut with facets that look like the steps of a stair. Examples of this cut are emerald, and baguette cut.

Symmetry

The symmetry of the diamond is the arrangement of the facets in angles. A diamond with perfect symmetry it also have perfect cut and perfect proportions that affect its brilliance. The gemological reports often indicate the symmetry of a diamond with terms like Excellent, Very Good, Good, Fair, Poor.

Synthetic Diamond

Synthetic diamonds are diamonds made in a laboratory and under the same conditions of diamond genesis. Synthetic diamonds are not imitation diamonds, but real ones with exactly the same properties as the natural ones. The difference is that we always have to mention their origin in the Certificates.

T

Table facet

It is the longest established facet in diamonds. Table facet is located at the top of the crown. This facet is sometimes called the "face" or "panel".

Tapered Baguette Cut

This is a a kind of triangular diamond cut with rows or elongated facets running parallel to the girdle. These facets are close to the girdle and the pavilion. In other words, this is a modified baguette cut.

Tension setting

Another kind of setting where the diamond has a predetermined position on the jewelry. The diamonds is set with nips that keep the stone secure in its place.

Tolkowsky, Marcel

Marcel Tolkowsky invented in 1919 the triangular proof that shows the perfect proportions of a round brilliant cut diamond, in order to achieve maximum its brilliance, flare and light diffusion. Tolkowsky-cut soon became the basis for modern American cut.

Tone

Tone signifies the intensity and color of a diamond. 

Toughness

The persistence of a gem. It shows how strong a material is in abrasion and breakage. 

Transparency

The ease with which the light passes through a material. A transparent object is defined by its clarity.

Treated Diamond

Treated diamonds are the diamonds that have undergone a process that improves their appearance. As treatment is defined any process that changes or improves the color and clarity of a gem.

Trigon

Trigons are concentric triangular developments that appear on octahedral faces of natural diamonds. These developments indicate the direction of the crystal growth. Sometimes we can see the remnants of these developments on the polished facets of round brilliant cut diamonds.

Trillion shape

A diamond with triangular shape and 50 facets. Trillion diamonds are often used as side stones.

Twinning and Twinning Line

Sometime a crystal can derive (in nature) from the combination of two different crystal structures. This phenomenon is called twinning and the crystal is called twinned crystal. The twinned crystals are formed by the union of two crystalline forms, which have common level between them, called twinning line.

U

Ultraviolet (UV)

UV is the visible to the human eye solar radiation that has a width of about 340nm. It starts at around 720nm with a red color and ends around 380nm with a violet / purple. Any radiation with wavelengths of less than 380nm is not visible to the human eye. UV radiation is of importance in gemology and diamond setting because it creates phenomena of phosphorescence and help us distinguish natural from synthetic diamonds.

Upper-Girdle Facet

Triangular facets of the crown that end up in the girdle.

V

W

Wavy Girdle

Wavy is the girdle that has no constant thickness and does not follow a defined imaginary plane in the perimeter of the diamond. A diamond with wavy girdle is not symmetrical and of less cut quality.

World Federation of Diamond Bourses

The World Federation of Diamond Bourses (WFDB) is the body that enforces the rules and regulations for the reliable and legitimate diamond trading all over the world.